Well that's a good sign. Seems Ren understood the assignment. That said, it's true that his vampire nature actually helps here. Especially since unlike in a lot of media, he can't get killed by sunlight, just get a really bad sunburn, and he's immune to crosses and most likely holy water.

"Satanael does have Heat Riser."

He does have other personas, but again, he's mainly focusing on only using Satanael due to both how strong it is, and also because there's nothing except almighty that can do any real damage.