He should keep talking, try to keep it distracted while he finds some way to escape. But the sight of the angel angers him, makes him want to fight, touches on the impulses that brought him here in the first place. He doesn't want to stand there cowering in the human form of his Cover, and so he casts it off, revealing his demonic bug form...

...and then he charges at the angel because he completely bombed the roll to keep his composure, intending to surprise it with an attack. He might not be able to score a clear win, but perhaps he can mess it up enough to injure it and escape that way.