OMFG, this is awesome... I love the composition, and the character designs (and also, I must admit, the fact that they're actually doing something from the book, as opposed to most fanart which just shows them lounging around).
Totally honest, I was just rereading this and I was remembering your cute cartoony versions of them while doing so, and hoping you'd doodle some more Good Omens stuff. That's a lovely miracle right there.
I think it's wonderful! My only points of consideration are that Crawley's wings are sort of flow-y, and almost too much so...I think they should be more jointed...Also, Azraph's weapon is more of a sword and less of a short sword/ gladius...it should be longer.
But then, seeing as this is a sketch, perhaps you aren't looking for cc.
And that's ok because it's a beautiful picture no matter what!!!
I tend to draw swords bigger but I also IDK thought about the swords of ancient times, and they tend to be short swords (which seem far less elegant and more used for buthery, which is sort of an aspect of it)