Once we get item wear, that by itself should open up a refinement of tools in a number of ways. Since the game track material properties in extreme detail, it only makes sense that you'll need harder tools to shape and sharpen harder materials.
To keep a knife sharp, you'll need a whetstone (a bag of sand also works), and also, ideally, some kind of oil or grease, preferrably fairly high grade mineral oil, if you want to keep from damaging the knife while sharpening it, and just keep an iron/steel knife from rusting.
To sharpen a series of tools for a
team of workers, though, a powered grindstone is more appropriate, because of the reduction in time involved, and also because of the unwieldiness of the axe.
Having tool maintenance be a normal part of work (work equalling here a series of jobs, like "cut down x number of trees until told otherwise), like food, water, and sleep, will add another aspect of Fortress management, but it's also something the computer can track by itself.
Dwarfs would visit the blade sharpening workshop, as part of their work-day, and the game would track the sharpness of their tools, in the same way it tracks how much alchohol a dwarf has had, lately, and then efficiency would be adjusted accordingly.
The job your dwarf performs with a tool that was sharpened immediately prior could be performed in, say, a third of the time. This would allow you to keep a set of razor-sharp tools ready for emergencies. The next 3 jobs--again, I'm just throwing out a reasonable number--would be done at normal efficiency, and then after that, job efficiency would be cut by half, and the tool might begin being damaged at twice the normal speed.
The jobs performed could be adjusted according to the hardness of the tool-material; but the harder the tool, the more time it takes to sharpen it, and the more specialized sharpener-workshops you would require.
I see sharpening-workshops (or whatever they'd be called) being only 1x2 buildings (one space for the grinder, one space for the dwarf), so they wouldn't take up a huge amount of space, and you could quickly set one up close to most job sites. Unlike food and drink, they might not use up any resources (they could, but this could also reasonably be hand-waved), so they should be fairly unobstructive.
In addition, dwarfs could carry whetstones, and there could also be larger, fully powered grindstones (powered by water, or dwarf-driven, or just hand-wave it with mechanisms, or whatever) that take up more room, but that can do the job much more quickly. You could have one or two of these set up in high-worker-traffic areas, like near dining halls, just to keep your workers at the top of their games.
There could even be a sharpening skill: This would be very appropriate, as sharpening takes skill, practice, focus, and consideration, in real life (I even sharpen my hoes and spades when I garden, and it makes a very noticeable difference in how easily they cut through just the soil itself). Practically every dwarf and practically everyone else would either use the skill on a regular basis (there are probably less skills that require or benefit from sharp tools, than ones that don't), or hire a specialis to do it for them (which was a real-life job that existed for hundreds of years, until the mass-production of cheap, high quality blades that stayed sharp enough, long enough, that noone minded too much just buying a new one when the old one got dull.).
In real life, infact, there are still a few Legendary sword-sharpeners who deal with maintaining katanas in Japan that are worth millions of dollars, and are considered national treasures--and the process of sharpening them is extremely specialized, to the point of being something of an art--and requiring exotic materials and practices.
Taking that to the next level: Not only sharpening, but the initial
shaping of tools made from harder materials should require harder tools, and swords and other forged metal pieces, were regularly sawed, filed, and sanded to shape, after the initial forging.
To move on to other areas requiring more refined tools:
More complex mechanism should also be required for more complex tasks: Boulder traps might require the simplest ones, while weapon traps containing a full ten weapons should really need something special. I'm also modding crossbows and seige weapons to requre mechanisms, and I'm going to have a variety of mechanisms, and other related devices (like block-and-tackle rigs, and water clocks).
More precise tools would be required to build these mechanisms, and should also be needed for magic-related tasks. Fail to inscribe a magic circle that conforms precisely to Pi, or whatever, and that Greater Daemon's gonna be laughing at you for a looooong time.
Other tasks that require high levels of precision are things like: manufacturing optics,
precise weighing (weighing coins for instance, as a part of determining the purity of the metal, but any merchant should have some interest in precision measurements),
earthquake detection (the ancient Chinese version),
loom manufacture, for advanced weaving,
creating alchemical tools (precise measurement again, but also the creation of things like complex valves, and complicated retorts, and precision grinding), and refining alchemical resources (mix too much sulfer or saltpeter into that charcoal, and instead of medicine, you might end up with an explosion or something!),
time-keeping (which can be applied to all sorts of tasks),
and the creation of fine musical instruments (particularly ones with lots of moving parts, like harpsichords, pipe-organs, hurdy-gurdys, what have you).
Concerning books.
I was going to use this suggested method exclusively for magic text, but it should work generically, as well:
Each skill could have books written on the subject, and these would be rated by Knowledge level, and Quality level.
Quality level would be how well written the book was; how accessible, how complete, interesting, and educational the subject matter therein.
Like anything else with quality levels, books would range from no quality (or tattered), up to Masterful (I'm going to disregard 'Artifact' as a quality level, just because it's not entirely accurate, and it complicates everything.).
Knowledge levels would range from Novice to High Master--Grand Master and Legendary would represent skill levels above what can be communicated through book-learning, while Dabbling just represents a dwarf that
wants to learn, but hasn't achieved any real skill yet.
The Quality of a book would determine the maximum skill points that could be earned by a dwarf for reading it (regardless of how many times that dwarf read the book), modified heavily by a dwarf's reading ability. The dwarf's Concentration would determine the percentage of total skill points a dwarf could pick up, with each reading.
The total skill-experience points a book would be able to bestow might be 50 skill points per Quality value modifier, plus 25 per Knowledge level (not including Dabbling), giving a 'Masterful Quality', 'High Master Knowledge' book a total of 900 skill points, or exactly half the experience necessary to reach Grand Master level.
This would be reduced by 50 skill points for every Reading level below Legendary+5, meaning that to get any benefit from reading the book, you would need a minimum Reading skill of Competent, and lower Quality books would be steadily more difficult to read.
The Quality level, starting at Well-crafted, would determine the total number of times a dwarf could re-read a book and get the desired benefit from it, although the act of reading a book with no Quality level would still raise the dwarf's reading skill, but would not contribute to gain in whatever skill the book was about.
Every level of the dwarf's Discipline, below Legendary+5, would reduce the skill gain by 5 percent per re-read, meaning that everyone with atleast Novice rating in Discipline could benefit from a single re-reading, but only those with Accomplished Discipline could re-read the book twice and still benefit, and it would take a Grand Master of Discipline to usefully reread a third time. However, the total re-reads allowed of even a Masterwork book would still only be 5--the maximum allowed even a Legendary+5 in Discipline.
This mechanism would keep players from cramming all their dwarfs into massive study-sessions, and would give Discipline a useful application outside of whatever military use it might find.
You could reduce this even further, by only allowing a book to be read a TOTAL number of times equal to it's value multiplier (so from 1 to 12 times), before it becomes illegible and unreadable by anyone. That would reduce the risk of "cram-sessions" even further, while making books that much more rare and valuable--and books were scarce, and extremely valuable, before the Gutenberg Press was invented, so mechanically enforcing a high value, and a certain delicacy, would be appropriate, as would giving strong incentives towards protecting and copying them (and enough expense and inconvenience to make it an appropriate challenge), for players who really do want to build a library.
To keep books from being lost in this fashion, and other ways (books could still wear out, or become damaged, reducing their Quality even without anyone reading them), you could allow limited copying of them by dwarfs with the Wordsmith skill, with the skill of the Wordsmith determining whether you have a perfect copy (equal in Quality, but never greater), or one of reduced Quality.
Even with the trouble of writing, reading, re-reading, protecting, and copying books, building up a decent library and promoting literacy among your dwarfs should have several concrete benefits, and might even be something that can affect diplomacy and trade, in certain subtle ways.
Ofcourse, having dwarfs who are as dumb as the stumps they resemble, and can't read their own names, might also arguably make a despotic dictator's job a little easier, so maybe the act of reading can occasionally cause unpredictable happy or unhappy thoughts, or even trigger Moods, so that you're still taking a few risks and chances.
I'm working on ideas for a magic system, and I'll be posting a thread sometime on books in general, and things like Occult Texts and Eldritch Tomes, in particular, to go along with it.
A suit of Renaissance field plate mail wasn't just some idea that pops into someone's head fully-formed ex-nihilo or from a book, it's a matter of the refinement of armor making techniques from centuries of constant demand. It's a refinement of tool and technique, alike.
(And I'd actually like to see us start the game with scale mail and banded mail and then iterative versions of chain mail...)
The best quality "scaled armour" generally speaking, was good enough that the societies that used it extensively didn't need to "advance" to plate armour. It's a nice example of parallel technologies, where there isn't only a single end-technology that everyone eventually hopes to get to.
Maille itself does this to a somewhat lesser extent, where efficient wire manufacture, combined with the best linkage patterns, and the best overall armour design, could produce a highly adaptable and adjustable product that was incorporated into many other high quality armours, and that by itself offered very substantial protection.
By the time plate armour reached it's zenith (arguably in Renaissance Maximilian armour), it was not only rare and extraordinarily expensive, it was also on it's way out.
It's pretty easy to claim that it did indeed offer complete and wonderful protection over every inch of the entire body, while allowing total, agile, freedom of movement, and as perfect weight-distribution as any body armour ever has.
However, this armour was rare, hideously expensive, each suit needed precise tailoring, and it was extremely difficult to dress one's self in without assistance. It also traded visibility for protection, and it was still heavy, stuffy, and prone to overheating and rust.
Scaled armour, or lamellar, on the other hand, was far more easily manufactured and fitted, was
relatively light-weight, and offered a fairly high degree of protection against slashing or crushing attacks, and even arrows, that a single layer of chainmaille atleast couldn't match, even with padding. It also tended to appear in warmer climates than gothic plate or chain, and better compensated for temperature changes. Obviously, the total protective value couldn't compare a suit of full, total-skin-coverage plate designed specifically for an emperor, and it suffered maille's problems with weight-distribution (and wasn't as flexible or adaptable, either), but it may have been a slightly superior technology, if argued in holistic terms.
Laminar, a type of lamellar exemplified by the Lorica Segmentata of the Romans (and similar Japanese armours), could offer even more protection than scale against certain attacks, and was slightly more adaptable because of the more regular metal strips, instead of rounded scales, at the cost of either flexibility and weight, in the lorica segmentata, or (in the very best O-Yoroi or other Hon-Kozane Dou Japanese armours) great time and expense, comparable to gothic plate.
I'd personally like to see armour be a lot more fleshed out in the game.