I like the idea of weapon attachment. It's cool. I don't mind that I might be stuck with a legendary carrying a no quality weapon.
But weapon attachment has caused no end of headaches (to Toady either, I'd be willing to bet). A great deal of problems attributed to the arsenal dwarf were no doubt due to weapon attachment, and problems still exist, while working around attachment is trivial, making the whole mechanic pointless.
1) When does a dwarf get attached? This doesn't need too much change, except for that time and/or training and/or non-lethal injuries are too large of a factor. Dwarves should get attached to copper swords; they should not, however, get attached to training weapons, and this happens when using an arena, because dwarves take so damned long to kill with a training axe. Ultimately, what we want is for there to be no way around attachment, but being attached to training weapons is too much. (Being attached to adamantine maces-- similar problem, but maybe, if you send a dwarf into an arena with an adamantine mace, you get what you deserve.)
2) Specific weapons are attached in the militia screen. This is a problem when dwarves start getting attached. Move them, and you don't move their attached weapon. Weird, hard to notice stuff happens as a result. So why not make attachment an exception to weapon assignment? Assign anything you want to a dwarf attached to a weapon: he will claim that weapon, he will carry that weapon, he will train with that weapon. But he will also carry his attached weapon, and when it's time to fight, he'll use the attached weapon. An attached weapon will not be available to any other dwarf for assignment, because it won't be a free item-- it will be an owned item.
3) Miners and fucking woodcutters. You know what I'm talking about. If they are assigned a military weapon compatible with their job, they should use it for their job. Period. Shouldn't this require only a small exception to the code? I don't want to see axedwarf woodcutters drop their axes to go wrestle deer. That's dumb. This is relevant to attachment mechanics, because mining and woodcutting should lead to attachment, and I believe they already do, but this is problematic when their weapon is also a tool. (Yes, attached miners should prevent other miners from using their pick. If you lose the miner, and you can't forge another pick, wait for him to die.)
4) Scabbarding. This is essential because of 2) above. Dwarves already carry flasks in their body armor; carrying weapons in their body armor isn't a far cry. (Backpacks, eh, doesn't make sense, and what if you want them to use the dining room?) So when a dwarf is assigned two weapons, or a weapon and a shield, and he has an attached weapon-- he can carry the attached weapon in the body armor. And when he gets in a fight, he can scabbard his assigned weapon and use his attached weapon instead. Yes, that does mean they'll be slightly more encumbered. I think they can live with it.
5) How do I get them to train wrestling? How do I get them to train in a different weapon? How do I get them to train in only their attached weapon? By assigning them no weapon, a different weapon, or a weapon of the same type as their attached weapon. They will still train with anything assigned. It's only when they fight that they'll break out the attached weapon. Yes, that means that you need a few more weapons. I think it's manageable.
6) But wouldn't it be cool if they only used their attached weapon sometime, and their assigned weapon sometime? Yeah, it would be cool. It would also make them less effective. I'd be down with it, but I'm sure a lot of other people wouldn't be. Wouldn't be something I would push, but I would be behind anybody who did.
7) No dump on attached weapons. These are owned items, same as socks. NO DUMP. NO MELT.