Crowley allows Aziraphale to take off the armor because, well, he never really wanted to be in it to begin with. He's not a soldier, he barely knows how to fight anything. He fell into the demon gig, he didn't want to fight. And now here he is, a fighter for the human race. Suppose it was always going to be this way.

He wraps his arms around Aziraphale. How do you restore faith to an angel that has lost it? How does a demon restore an angel's faith? Crowley held onto his own sort of faith in an awkward kind of way, but he never kept very good care of it. Now he needs it more than ever.

"You saved the world," he says. "You do realize that, don't you?"