I generally don't mind my Vereth's aftermath only proc'ing on the Offhand (this was also confirmed by testing on BG, so your observations were spot on). The weapon as a whole is still so much more powerful than any other alternative that I certainly can't complain. I see it more as a balance tweak than any sort of nerf. If the Aftermath could proc on both fists, every other one-hand Empyrean user would be up in arms.