i wonder if anyone uses those feats. i think they need some improvements. some classes already have or will get fortification lowering attacks/feats so how about adding this effect to sunder (lets say 15%) and imp. sunder (30% here)?
this effect shouldnt work on constructs (we have rogue wreck construct) and undeads (unless u are hunter of the dead II maybe?)
we could get stalward defender/defender of syberis PrE contribution to fortification like +10% per tier (it would stack with 100% item allowing them to get greater fort. than warforged dps build)
is it stupid? i dont know. you will decide.
i think this could change end game fights. some mobs are using this attacks against players so even if u have 100% fort. AC would matter now in case of critical hit confirmation (warforged can get 125% fort. now so maybe there should be 25%/50% fort decrease for sunder/imp. sunder). this could make players think twice before letting barbarian tank the boss. it would also make fighters more important cause they can afford improved sunder easily unlike barbarians.