Well. This story could be great, but in the end, it's just a harem fanfic with uninteresting main characters, a ton of cliche and easiest power struggle out of there.
I liked how thoughtful you was in power description. I liked how you make use of them
I liked characters for harem *. I don't like how easily he gets them. I mean make them brainwashed lovers ,and mc getting all white of how he dislike it, but still need they powers ....yeah, I cringed hard, but at least it's was glossed over fast.
And then there is story itself and mc. Why he doing anything he does ? Because it's best option? Yeah, sure. That's the problem, I don't feel like mc have more in him, than just conviniet function to make good decisions. The same with his character changes*, when he introduced flames, I was already iffy. But when he reminded of sky flames...i just realized how deep the rabbit hole. Either way, story don't have much tension or interesting moments.
P. S. When you go in dxd and create harem only from the girls you summoned from another world(and Valerie, I dropped it) ....what? There is no good girls in dxd?