I see no reason to worry, for we are not mere mortals. With the Dreamer on our side and the powers granted by her, I would not be surprised if we ended up going against Zariel and ending up in a stalemate.
We are after all going against Cazador, the three Drow Chosen, the Absolute and who knows what else. We are meant for great deeds, so a smackdown with Zariel in some shape or form would not be unimaginable as we most likely will be powerful enough for it, though I would settle in just meeting her.