Urist da Vinci has a very interesting thread over in the modding sub forum about material properties and game mechanics as analyzed by dfhack. Here he's talking about weapon momentum in traps:
Unrelated, about traps:
The velocity of a weapon trap attack is always 200, so the momentum is:
momentum=200*(weapon weight)
The mechanism quality doesn't seem to change the momentum of a hit (but does affect trap accuracy). Note that creatures will swing heavy weapons slower, but traps swing all weapons at a fixed speed. A weapon trap swings an axe about 10x faster than a dwarf could. Therefore, weapon traps will perform better when equipped with the heaviest weapons you have available.
Apparently, due to some oddities of trap mechanics, all weapons in traps move at the same (fast) speed regardless of weight, unlike wielded weapons that have a swing speed dependent on dwarf strength and weapon weight.
Therefor dense, low grade weapons metals like copper, silver, and bronze would make excellent trap components. Make war hammers, maces, and spiked balls from silver. Spiked balls are largest, so should be best (requires testing), and are technically edged, but will be converted to small contact area blunt against armored targets. Make serrated disks, axe blades, and other edged things out of copper, or better, bronze.