I did some large-scale testing of melee weapons, because I wanted to know what would be the most effective thing to arm my dwarves with. There are some results posted on the wiki, but I'm not sure how old they are, and Toady fixed several bugs relevant to melee combat so even 34.11 results might not be accurate any more. Short answer - all weapons besides maces are pretty similar - maces are crap (I think that's pretty well known).
In this test I wanted to see what would be most effective against invaders. I made a custom arena with an array of 1x3 cells across the whole map. I then placed goblins in each of the cells, like so
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where 1 and 2 are the goblins on sides 1 and 2. For all tests, goblins were armored with iron helm, iron chain mail shirt, leather leggings, and leather shoes and iron shields. In other words, fairly typical for what invaders wear - perhaps on the high end. I then added 1152 goblins for each side, armed as described, using macros which I will post shortly. All goblins were competent in fighter, axeman, swordsman, spearman, hammerman, maceman, dodger, armor user, and shield user.
Edit: I forgot to mention that I used a script to count the first 1000 kills in each test, and tabulate how many were for each side. I stopped at 1000, as if you wait long enough almost all the test subjects on both sides will die from bleeding and infection, so you have to stop somewhere. I then ran most of the tests twice, switching which weapons was side 1 and side 2, in case there was any bias between sides (it appears that side 2 gets to strike first, and has a slight advantage), and added the scores together.
The results are as follows:
For steel weapons:
axe | 836 | sword | 1164 |
axe | 789 | spear | 1211 |
axe | 1305 | mace | 695 |
axe | 943 | hammer | 1057 |
sword | 944 | spear | 1056 |
sword | 1422 | mace | 578 |
sword | 1069 | hammer | 931 |
spear | 1368 | mace | 632 |
spear | 1137 | hammer | 863 |
mace | 728 | hammer | 1272 |
In older versions, heavier metals made better blunt weapons. However, Toady fixed some errors which I think were largely responsible for this. Any difference between silver and steel blunt weapons is small enough that it is not statistically significant.
silver mace | 1019 | steel mace | 981 |
silver hammer | 991 | steel hammer | 1009 |
However, adamantine is light enough that it is significantly worse for blunt weapons, and of course it is a bit better for edged weapons. I suspect that there is something like a cutoff for the maximum speed a weapon can travel at (this is what happens for projectiles) such that very light things like adamantine (and possibly wood) end up with lower momentum, but all standard metals are the same. This is purely speculation though.
adamantine axe | 534 | steel axe | 466 |
adamantine sword | 536 | steel sword | 464 |
adamantine spear | 509 | steel spear | 491 |
adamantine mace | 214 | steel mace | 786 |
adamantine hammer | 159 | steel hammer | 841 |
In summary, spears appear to be the best melee weapons, followed by swords, warhammers, axes, and finally maces. The differences between the good weapons are quite small, and may not even be significant in all cases. These results are for goblins armed as "typical" invaders, and it is possible different weapons could be better against other opponents.
My next step will be to test against larger creatures, such as elephants, dragons, and (if I can figure out how to get the raws) maybe clowns. Given that spears came out on top against goblins, and they have the highest penetration depth, I expect that they will also prove the most effective against larger creatures, meaning they may be the best overall choice for your military. However I cannot stress enough that the difference between all weapons (except maces) are quite small, so you should not take these results to indicate that other weapons are bad.
For comparison, I ran anther test where the skills of one set of goblins were Great and the other unskilled, and both sides had silver hammers. The result was 999 to 1. Skills far outweigh the small difference between weapons, as the standard weapons are actually balanced quite well.