Okay, moving on from whips, let's check out spears and some more MAX_EDGE stuff.
Spears and pikes seem like a good example of how armor is too strong: Iron pikes/spears simply cannot penetrate iron mail shirts, much less breastplates. This renders the purpose of a spear pretty moot. I'd think that the low contact area of a spear plus its sharpness would help it penetrate armor, but this might not be working as well as it should, perhaps?
However, spears and pikes seem great against unarmored and lightly armored opponents. Against no armor, or even leather armor, they're great at stabbing straight through a body and tearing into organs, not just bruising them. Against tin chain, they also seem to do okay at this, even if a tin breastplate is placed over.
I think the main problem is just that they can't seem to penetrate armor at all once it reaches a certain level. Adamantine can pierce straight through iron chain+breastplate, despite its lack of weight, and that's good.
Steel spears vs. iron mail+plate seems to result in a lot of piercing below to the fat and sometimes muscle, along with a few (but significant number of) hits to organs. Organ tears happen much, much more often when it's just an iron mail shirt and no breastplate, or a breastplate with no mail. The second I change the armor to being steel as well, though (even just chain), the steel spears start to completely suck at penetrating at all. Lots of deflection and force-transfer bruising results (this is true for pikes as well as spears, it seems).
Conclusion: Spears and pikes kick all kinds of ass, tearing up organs and shattering skulls and brains, but only when the armor is worse than the spear in terms of material. Once the armor reaches the same material quality as the weapon, though, serious wounding through penetration becomes all but impossible. Highly-skilled dwarves will still break bones every now and then, but not through penetration, only inter-layer force transference.
To some degree, I think these results might be realistic. I don't know how good spears are in real life for piercing through similar-quality armor, but I want to say that penetration should happen at least every once in a while, as opposed to never.
Keep in mind that, as with all these tests, I'm using the arena mode, so item quality isn't coming into play at all. I have no idea how much it would matter if the spears and armor pieces were all exceptional-quality, or anything like that. Presumably, the weapon's edge would be sharper, but I don't know about the armor.
Also, I did some tests mucking about with weapon density and MAX_EDGE. Changing gold to have a density of 1 understandably resulted in them basically having LARP boffer weapons, never doing any damage to anything. If I do this and also give the metal a MAX_EDGE twice that of adamantine, they still only dent skin. Just food for thought, trying to figure out how this works.
However, changing gold's MAX_EDGE to extremely low values seems to do very little, testing out golden shortswords and spears. This goes for other materials as well: I changed steel's MAX_EDGE from 10,000 to 50 (!), and it's still tearing organs straight through iron mail shirts. I'm not sure what's going on here, unless MAX_EDGE just isn't actually affecting much.
[EDIT]
Seems that bronze spears can pierce iron chain/plate surprisingly well. So, bronze edged weapons seem to beat iron weapons in terms of penetrating armor. This is probably realistic, actually, but it seems that maybe humans and goblins should use bronze more often in light of this.
Really, it seems that spears/pikes are mostly okay except for the pandemic problem in the new version of armor getting way, way too good at resisting penetration past a certain threshold.