I'd vote for: Complex Weapons [Such as lead-core staves and such, which require an 'intermediary' object. IE, lead+iron= Leaded Iron Sphere + Log = Leaded Staff, or Log + Iron = Capped Staff, or Log = Staff, Metal = Large Blade (trap comp) + Log = Pudao/Kwandao ('Dwarven Halberd')]
Better, stronger weapons should require more worksteps. If they appear in the same menu in the forge as everything else, no one would make normal/weak weapons anymore. You could make parts, and then assemble that parts:
Produce (axe/sword/halberd/whatever) - blade.
Produce handle/stock.
Make both of them use different materials, in this case metal for the blade, and wood+leather for the handle. Then assemble them using "get_material_from_reagent" from the blade-part, to get the right weapon. Ignore the handle materials, because they are always the same anyway.
Essentially what you just wrote, I got carried away thinking about it, sry.
(rant) A point I want to add about the metals: Normal DF players know which metal is good/bad for a certain task. Noobs have to look up the wiki, to avoid candy cotton hammers... what I am getting it is this: Realistic metals are nice and fit the DF theme, BUT no one will know how good it is/what it is supposed to be for. Fantastic metals could have an informative name, giving the mod-user a hint. If you add an alloys for every metal, with a default adjective that is always the same, then people can learn it easier. Example: Black steel = better then steel, black bronze = better then bronze and so on. It is not realistic, but userfriendly. (/rant)