Basic suggestion thread. I think that there is not enough weapons in the game, and that some of them need improvement. The point is to allow players to have a more advanced military strategy.
So here it goes:
Making a new axe type, the "War Axe", or the 2H axe, that would do more damage, would have a larger range and better block chances, but of course, no shield allowed.
Giving more attack option to a dwarf who is holding two weapons. Surprise attacks, harder to block, etc.
Making more types of shield. Some should protect more against arrows (large, heavy, rectangular ones) while some should be more useful in melee combat.
Making halberds possible to build in dwarf mode. Now, an spear has a size of 400, an halberd has one of 1200. It could be an interesting mix of the axe and the spear.
Making daggers a common dwarf weapon, and allowing your dwarfs to have one without needing to hold it (You put that on a belt and everything will be ok, Urist) so they will be able to take it if they loose the original, main weapon.
Changing the siege engines. They should be able to shoot through z-levels. For now, they are not really useful if you want to be "imaginative" in your fortress defenses.
All of these to make the military system of a fortress more... Customizable.