Crowley wasn't positive what would happen to the Angel either, if he was able to get to the sins in his soul. She had never known of a case of an unFallen Angel who was Tainted, before.
"Good. The Angel tells me your instincts will take over, and allow you to do what is necessary to absolve him. You may do what you must, in order for this to work, but I will stay in the room and supervise what is going on. Make sure that everything remains in control, and that you don't take advantage of my pet."