[Who, indeed. He'll let Kuai wonder, for he has no idea. A spirit? Maybe. One of the others? Honestly just as plausible given his brother's personality. Self-defense. But he's not going to say that aloud.]

I've never seen the church spirit fully, no. Just a glimpse. Its hand slipping through the trap door. If you're quick enough to open your eyes you can catch that much before it leaves. Nothing more, though. I'd ask Aziraphale, if I were you and wanted to know details. If he doesn't know them personally he might direct you to someone who does.