Her feathers don't kill them completely, merely stagger them and distract them, long enough for Xayah and Crowley to get the people and Bucky to shoot the guys that are not paying attention to him.

She flies over to the door and places the person down and then tries to back up Bucky because those things are close to swarming him. She's seen enough wild magic to be too surprised by flying knives and other crazy cutlery- the more of the chaos, the better, it keeps spirits' attention to it, instead of the sleeping people.