I've thought about this too, and possibly a knock DOWN state, similar to fallout 1 - 2. hard, or bad hits on low hp, or bad footing causing one to be temporarily incapacitated. not exactly knocked out, separate from knocked out, but just fallen down, set to get up next turn, and adding a little stun / energy loss. This in particular could make for astounding melee, Imagine in piratez stumbling a power armored unit long enough to bring a can opener.
Also rather than damage v strength and armor, maybe damage vs mass of unit, plus a multiplied melee number, and a reducer in knock down for armor effectiveness, and a small amount of morale taken into account, to base off flinching.
For melee, take into account melee skill of individual, and strength too.
....course this would be a lot of code.