Castiel shook his head. "It would have no effect. My Grace imbues this vessel with a certain form of both healing and invulnerability. But if that is what you prefer, I will be careful."
He did wish somewhat to point out that even his best friend had shot him during their initial meeting, but...it seemed unimportant for the time being, so he let it slide. Dean had not realized what or who he was at the time.
"I can," he confirmed. "I can hear all of the prayers of those who truly ask for me and I do listen. Most would imply I do not, but...I will hear you. Of that you can be certain."