v34.05 Weapons vs Armor
See the forum thread.
For me the reason of the difference between the blunt weapons is the contact area. If you look at it, it explains the difference from you weapon testing. Whip being best, maul being worst.
 v31.18 Combat Research
I did some !!SCIENCE!!. Results obtained from 31.18, but should still be valid (the combat system hasn't changed, as far as I can tell). --Shinziril 04:55, 15 June 2011 (UTC)
Fighter and Weapon skills give both increased offense and defense (parrying happens quite a bit if you are more skilled than your opponent). High Fighter skill is much better than being completely untrained, but is trumped by high Weapon skill (particularly given that Fighter trains at the same time as Weapon skills, and faster to boot).
High Dodging skill is a massive advantage in combat. If your Dodging skill is above your opponent's weapon skill, you are almost guarenteed to win the fight. Even if it is only the same or below your opponent's weapon skill level it still gives a noticeable edge. A recommended training regimen for adventurers is to find a groundhog, monkey, or other small, inoffensive creature, grab it to prevent it from running away, and then let it flail wildly at you while you practice dodging. Extremely high opposed weapon skill levels seem to decrease the benefit of high Dodging skill levels, but these are rarely encountered in practice.
Wrestling is near useless when used by the AI. Its most common maneuver is to grab random body parts or articles of clothing and then release them. Code that makes people with open hands favor using those to wrestle would likely help here, as then joint locks and gouging would be more common. As it is, the AI will gouge or execute joint locks if it manages to randomly use hands to grab a relevant body part, but is otherwise not very effective. It will also attempt to strangle if it grabs the throat (again at random).
In the hands of a player, however, wrestling is vastly powerful. An unarmed enemy dies horribly versus an armed opponent, and with a free hand, a player can wrestle an enemy's weapon away from them. Currently, the AI cannot pick weapons off the ground, so this renders the disarmed enemy near harmless. Even if this is ever corrected, a high enough wrestling skill would still likely allow you to play "keep-away" with the enemy's weapons.
A player can also go for strangulation, which is highly effective. A good chokehold takes down any enemy that breathes within a few combat rounds, rendering them entirely helpless and easily killable. If one has a high enough Ambusher level, it is possible to sneak up to someone without them spotting you, knock them unconscious, and swiftly dispatch them, all while remaining hidden. Of course, this method does not work on anything significantly larger than you are, or that does not need to breathe, which includes pretty much all night creatures and megabeasts.
Unarmed combat can work, but it is significantly less effective than an actual weapon. Most reports of success in Adventure Mode involve combinations of this with wrestling to render enemies unarmed or unconscious. If you must use unarmed combat, remember to aim for headshots, as unarmed combat is a blunt weapon and shattered skulls/torn brains are the main effective method of getting kills with blunt weapons. Also, if your skill in unarmed combat becomes high enough, you will start to use it more and more even while wielding an actual weapon (due to either opportunity strikes or your unarmed combat skill being higher than your armed combat skill).
 Weapons and Armor
The tiers of materials for both weapons and armor are Adamantine > Steel > (Iron = Bronze) > Copper > Silver. Blunt weapons mostly ignore this tier, and are effective almost no matter what they are made out of so long as its density is significant. While increasing density makes blunt weapons slightly better, any weapons-grade metal other than adamantine is acceptable for them due to the narrow range of available densities. Ammunition follows the weapon tiers with the exception that adamantine bolts are too light to do any significant damage.
Weapon attacks are functionally divided into three categories: blunt attacks, "slashing" attacks, and "stabbing" attacks. Blunt attacks are obviously any weapons with the BLUNT descriptor. "Slashing" attacks are edged attacks with a contact area of 50 or greater; it should be noted that this includes the "stab" attack of all swords. "Stabbing" attacks are edged attacks with a contact area of less than 50 (and preferably a high penetration depth). In vanilla DF, the largest contact area below 50 is 20 (pikes and spears).
Blunt attacks seem to ignore armor of the level of iron or below, are somewhat blocked by steel armor, and are often (but not invariably) blocked by adamantine armor. This seems to be mostly independent of the weapon material. Blunt weapons are somewhat worse than edged weapons against unarmored opponents due to the lack of bleeding. Always aim for the head to get crushed skulls and torn brains, as these are the only instant kills easily available with blunt weapons.
Slashing attacks are almost completely incapable of penetrating armor of the same tier as the weapon or above. Picks with their higher velocity multiplier seem to be the sole exception to this, and even then the damage mostly consists of bruises and the occasional broken bone, indicating that their normally edged nature is being converted to blunt damage by the armor. Quite realistic, really. However, if the slashing weapon's material is of a higher tier than that of the armor, it will cut through the armor like butter. Note that this means that steel battle axes currently trump any enemy armor in vanilla Fortress Mode, as no enemies of the dwarven race naturally have access to steel armor. Be warned that this may change once dwarven armor sales to outsiders get tracked properly. Similarly, bronze or iron armor is sufficient for protection against slashing attacks in Fortress Mode, although steel armor offers mildly superior protection against blunt attacks and is thus still desirable.
Stabbing attacks can penetrate armor, with the degree of penetration going up as the contact area goes down. The level of armor that can be penetrated depends on both the material of the armor, the material of the weapon, and the contact area of the attack, but a good rule of thumb is that a stabbing attack can penetrate armor of at least one level above the material of the weapon. It may require a decent degree of weapon skill to do this, however, and extremities like the hands and feet seem most vulnerable. Note that morningstars are actually stabbing weapons with a contact area of 10, and large daggers have the uniquely small contact area of 5 on their stab attack. Large daggers can thus make effective anti-armor weapons (watch out for those goblin thieves!). Ranged ammunition and meat preparation knives and forks also have very small contact areas and can punch through armor (with the obvious exception of cleavers). It should also be noted that the small contact area that allows stabbing attacks to penetrate armor makes them less likely to sever body parts, but since brain death kills everything with a brain, I find that this is not a problem.
Penetration depth does not have a huge effect on human-sized targets, but for large targets such as giants, dragons, or other various megabeasts it becomes essential if you wish to reach any interesting internal organs (including brains). The fact that increasing size also renders severs and decapitations significantly more difficult means that stabbing weapons such as spears have a noticeable advantage when fighting large targets such as megabeasts. Again, aim for the head to get brain shots. The only exception to this rule is bronze colossi and other large, sturdy randomized beasts without brains or other internal organs to target. For these, you will simply have to settle for cutting off their heads through many, many hits with a slashing weapon, lumberjack style. Make sure your axe is stronger than their body tissue!
Robes protect every part of the body except for the head, hands, and feet. Modded pseudo-adamantine "leather" robes protected perfectly against slashing weapons in arena mode (with the addition of adamantine helm, gauntlets, and boots to cover the remaining body parts), but testing is needed to see if true adamantine robes retain this property.
The current combat AI will always go for headshots while an enemy is unconscious. Thus, if the enemy is wielding a weapon which cannot penetrate your helmet and you are unconscious, you are completely safe. Note, of course, that blunt weapons will almost always penetrate eventually (even if they're just punching you).
Miscellaneous object users wielding two shields had an advantage over miscellaneous object users wielding only one shield.