Ragnarok

She got initial credit for it because Gunn and Connor saw the sun return and assumed she'd done it. I'm pretty sure Wesley gave everyone the true story in Release, and I sure don't remember her running around claiming she'd done it.

I'm not the world's biggest Faith fan, but let's give credit where credit is due. Angel had thrashed her pretty thoroughly in Salvage; she had committed herself to not killing him so she was at a disadvantage in a straight up fight. She injected herself with a dangerous drug in order to incapacitate him when he drank from her, to give the others a chance to capture Angel and figure out a way to restore his soul. I don't know whether it all adds up to heroism, but it was resourceful and not especially self-serving