I don't know your inmate, and I'm not going to stop you if you want to restore her abilities. And while I'll fully admit I don't know Arthas well, the fact that he used his powers to lash out and attack others means I'm not going to ask for his abilities back or expect anyone else to do so either until he proves he won't endanger the lives of others.

But I do know Erik. And I know that he was in port, with his full abilities, and didn't go on a rampage, slaughtering humans because he was angry and lashing out at the Barge, or whatever it was Mr. Menethil thought he was accomplishing. He knows restraint, he can control himself and his abilities, and again, denying him what is fundamentally him is just making him angrier and more likely to snap the longer it's kept from him.