I can't imagine why you would want to keep steal essence when awakened. Iss Enchanter becomes a melee class. The skill crippling attack reduces your targets physical and magical defense by 30% in PvE and 40% in PvP. Also Iss Enchanter can almost continually spam Healing Melody (chain heal) on themselves / friendly target.
Crippling Attack is a necessary skill. In PvE, you will kill mobs so much faster (and believe me, mobs rarely resist it). In PvP, it's just broken. -40%PDEF/MDEF with a low cooldown and a high base landrate. You'll be smashing serious face.
There is no reason to keep Steal Essence, you stop being a nuker class and get warrior stats, so it ends up being subpar all-around.
Also, you cannot keep Great Fury. It's lost either way. I had Great Fury as well, was sad to see it go but that's just how it is.