... a solution that doesn't involve massively powerful weapons? Exorcisms would work the same way as anywhere else (only stand well back when they take effect; supernatural entities don't necessarily wake up well). Depending on the entity, they might be susceptible to tranquilisers, chloroform, etc to make it easier. Heck, even acting like a bumbling idiot, pretending you think they're a famous author, and asking for their autograph would get you near enough to exorcise, easy.

Killing is different, but not necessarily harder. [Has now glanced at the 'fic] There's dozens of continua where angels can be killed -- if you can't think of anything better, just drag her over there and stab away. Or you could tempt her with something she can't resist (she's a Sue, shouldn't be too hard), then point out that she's just become a Fallen Angel and violated her character description; with luck she'll implode from logic overdose. Or you could borrow a hero from an Eddings book, they're prone to killing divinities and their servants. Or... dozens of things.

hS