Castiel was breathing heavy by the time he banished it. He was standing rather awkwardly in an attempt to stay vertical. He wasn't exactly used to fighting demons daily without any of his powers. He was like a sitting duck here. He was going to have to talk to Sam and Dean about this.

Once the smoke cleared and Rose was still he dropped to his knees and made his way to her. He picked up her head and let it rest in his lap. He looked down at her with worried eyes. "Rose?"