attacks that damage health simply do less when you have armor value. The math that you don't want to see also tells you that resisting specific attacks is better than trying to out-armor them. What that means is that things like the root chest with the heaviest other pieces you can get is better against pierce attacks (which are common esp in mistlands or all archers/death squitos / spear tosser guys / etc) than pure heavy armor, and that vulnerability is pretty bad to have.