I had wanted to respond to this a while back, but for some reason just didn’t. Let me remedy that now.
I realize this might have been a purely hypothetical thing, but if you ever did want to have Duncan meet a friendly angel, I’d suggest the Archangel Jophiel, actually. Similar to Luzurial (down to wielding a flaming sword), but with the benefit of not having been made up by JayDee or me, and of having an actual Hebrew name!
Jophiel’s name, יוֹפִיאֵל, translates as “divine beauty”, and as such the angel is commonly depicted as female. She’s listed by Pseudo-Dionysius as one of the seven archangels (along with Michael, Gabriel, Raphael, Uriel, Camael and Zadkiel), but I suspect she would have counseled against attempted deicide because Jophiel is the archangel of wisdom, understanding and judgment.
She hasn’t shown up yet, but in the WitS universe, Jophiel is one of the seven vessels (the seven archangels), and her appearance is based on this stunning piece of art by Lorenz Basuki. I don’t know that it’s a specific archangel, but the first time I saw it, someone was using it for Jophiel, and the image stuck.
Uh...I realize that sounded like I was pitching the character. Sorry if it sounded like I was pushing. Duncan’s got other things to do for the moment!
He’s gotta talk to a spider.
On the subject of Duncan himself, you mention that an angel, or archangel anyway, could see the damage done to him. Can others? Is it visible to his husband, for instance?