Originally posted by SupremeMan
He got the powers back from "Osiris" (now there was a name giving away his fate if ever there was one) because he had divided the power with him. Taking them back just put BA at his normal power level again. I don't remember exactly but I don't think he divided his power with Isis. He found some other way to give her powers.
Isis power was granted through an amulet given to her by Adam. Osiris power was given to him by Adam, and when he died Adam received that power back making a statement similar to "I feel stronger than before" or something.