First off, thanks for the in-depth commentary! Posts like this and Urist's testing and commentary really help mods along, as I will undoubtedly miss flaws and potential opportunities.
I actually have seen most of Scholagladiatoria's stuff along with that of Lindybeige and Skallagrim, they make some very informative and entertaining stuff! Quite a bit of the research of this mod came from these guys, along with wikipedia, myarmory.com and various other sources.
Your points on weapon length are entirely correct. Sadly actually keeping enemies at bay with a longer weapon is just impossible to mod in right now, but the weapon length-to-prepare-time is actually already in the mod. Its just a bit hard to see from game itself. An arming sword for instance has 4:2 on both stabbing and slashing, whereas a halberd has 1:5 for stabbing and 1:7 for the hack/spike attack to account for the considerable momentum of the weapon.
Daggers and short one-handed weapons get 5 prepare time, medium length one-handed gets 4, short two-handed weapons (longswords, longaxe, etc) 3, medium-length polearms (most spears, poleaxes, etc) get 2 and long polearms (halberds, pikes, etc) get 1.
The item descriptions will make this a bit clearer, they give a short summary of the weapons properties and their attacks.
(This I all typed as I was thinking, sorry if its a bit rambly)
I was actually thinking of reducing the number of weapon skills for some future version, leaving weapon skill unused doesn't seem to have any particularly bad effects on the game.
What I was considering was just using the pike skill for all two-handed weapons, spear skill for one-handed spears and sword skill for the rest of the one-handed weapons. I didn't think of the tree-chopping problem, though I might be able to get around that by adding a felling axe as a tool instead of a weapon and renaming the axeman to 'woodsman' or something (or if that fails as a training weapon). I really don't want to make it possible to cut down a tree with a mace
I considered moving one-handed weapons to the dagger skill to force the AI to use them as side-arms but the entity soldiers and such don't actually spawns with dagger in the first place so that would only cause them to pretty much disappear from the game. Not really desirable or realistic, while less common dedicated swordsman did exist. I sadly have pretty much zero control over what the AI places on soldiers so better to have them in poor proportion then not having them at all.
There's a couple issues there though. For one, I have no idea what to do about the names. Invading squads are going to show up as an absolute mish-mash of weapons, etc etc.
On the weapon-skill sets you posted: I would at least merge sidearms+axes, longspear+poleaxe+polehammer and longsword+greatarms.
Axes because I can probably circumvent the wood axe somehow.
Two-handed polearms are all fairly similar, in fact the poleaxe, polehammer and bec-de-corbin/crow's beak are historically all referred to as 'pollaxe' and are described in single entry of the various arms treatises (the art of using them referred to as 'Jue de la Hache', or 'Axe Play'). The reason I split them up is because having five weapons with the same name would get all sorts of confusing.
Longsword and two-handed axe/warhammer/mace are... not entirely similar, but having longsword as a single skill seems inconsistent as the other skills cover a fairly large number of weapons.
I wouldn't mind splitting up two-handed non-polearms and two-handed polearms. At the very least it will make naming a bit easier, and Mount & Blade made it work so why wouldn't DF. Lets see...
Armsman (sword skill) - One-handed weapons.
Greatarmsman (axe skill) - Two-handed non-polearms. EDIT: derp, NOT axe skill, but mace or hammer.
Spearman (spear skill) - One-handed spears.
Stavesman (pike skill) - Two-handed polearms.
'man' can of course be replaced with 'dwarf' and such.
The problem with that however is as you mentioned that only the pike skill prevents the whole 'two-handed sword + shield' soldiers, which I kinda hate seeing. The whole entity equipment in general is sort of a trainwreck though. It just picks one single body armor, one single helmet and uses that for every soldier for that entity. No arm/leg protection, it will completely ignore armor levels (I have had them use a greathelm with a gambeson) and dagger don't actually seem to get used anywhere.
Regardless I think I will give this idea a try, at least after I finish up those item descriptions, address a few balance issues and do some work on entity equipment distribution (which is a bit of a mess now).
If anyone can think of a name covering
all two-handed weapons, I'd gladly hear it!
EDIT: I wonder what it would do if I hijacked the blowgunner skill for one of the two-handed weapon classes... They don't get placed with shields, though also often not much armor...