There have been several nerfs, but also multiple buffs in varying ways. Two years ago, archers weren't able to do pierce damage for example. A few months ago, 6PD builds were capable of the same damage as a 10PD build, thus pigeonholing archers into only a couple of different builds without taking a gigantic hit to effectiveness. Instead of simply lowering the damage that 6PD archers do, they gave all archers more wpf. They changed around light armor weight amounts so that you weren't stuck with either a 4 weight chest or a 10, with nothing in between. They lowered the maximum amount of armor that melee can obtain, particularly by nerfing armors that only melee characters use. All throwing weapons obtained the itp_extra_penetration property, including cut damage throwing weapons.
That's off the top of my head, without asking anyone else or without looking up past threads.