[@VitaVitaAR] The sword was honestly thrown in because I realized she didn't have a magic weapon. I haven't devoted a lot of thought to what it was yet, and it went with her fire theme. Highly negotiable. I can find something else for it.

The rest, on the other hand...not so much. Kael isn't a feature of any established setting (that I know of, and if so it's quite incidental), but meant to be the name of a small town which pretty much no one has heard of. It's got zero development apart from being named Kael and being where Charlotte grew up. You don't necessarily have to slot it anywhere if you don't want to. Small town. No real narrative value. Source of a name and an origin. The name isn't changing, but you don't have to bend over backwards to fit it into the world.

"Fallen angels" don't exactly fall by the spewin' wicked fire dealio. It would be a massive conceptual change to swap from demonic origins. Her title is literally "hellknight." How much power she has and what she can do with it? Totally workable. But where she gets it from is sort of a fundamental portion of her character. I'm not sure how much wiggle room that leaves.