I always love to hear about not-so-flawless angels, aspects of something that's not always pure and blissful light, so I like Liesa's concept; her PoV is nicely introduced by a loving description of a sunset (love the "sick gold" part in particular) that of course an angel of DUSK would appreciate
The ending isn't that unexpected in substance if not in form, as an angel stooping to deal with a demon is bound to either be corrupted (which she debatably is) or get monumentally screwed, but that doesn't mean it doesn't work well.
I have to admit I don't know Innistrad's Who's Who too well, so I had to google a few of the names to understand the references, but that's a me problem. I wonder whether the magic of the deal is broken by Liesa's end, because it's not immediately obvious.
To sum it all, it's a neat character piece for a forgotten character - an act of justice I commend - in Innistrad's tormented history, and I quite like it! Thank you for sharing.