"Wouldn't it be an angel of the Lady if she's a 'she'?" No. That's not the important detail to fixate on. Jon blinks a few times, looking Aziraphale over with more genuine and less... eldritch curiosity. Then, he looks around at the rest of the room. No one seems to be gaping at the other man, so that would appear to be a contained effect.

"I've met plenty of demons here. You might be the first angel. Can you still feel your god's presence here?"