Felblade and Firstblade have been the most annoying talents to me since neither really seems to have a strong "this is what you use this for". Even in AoE you still are using First Blood for ST damage.
I honestly can't decide which one is the better dungeon talent. Blade Dance will be stronger on trash and the higher use will give better fury over Fel Blade but will be a St nerf so bosses will lower but trash will be higher.