Jesus Christ that is so fucking stupid. So now the literal only reason she turned is to have a dragonball Z plot armor power up to stay as powerful as the MC.
I'm going to die on the fucking hill she would have been a much, much, much better character and plot device if she stayed human and was used as a beacon for the MC to remain truthful to his human side as he grows stronger in powers. She could have been the link that ties the MC back to the human part of himself, but no. Power ups and damsel in distress go BRRRRRR.
Yeah no fuck that, Eliza always being weak, in danger and a target is such a lame storyline which we had already.
And tbh this avn has a dbz vibe from the early beginning, i mean look at the devs name or the way the MC powers up, its just red eyes instad of yellow hair, imo its part of the charm. It even has the same inconsequential powerlevels (aka mc barely beats two bandits but easily destroys the magic ninja assasin).
I can only encourage you to give it another chance and see if its really not to your liking.
And tbf the purified vampire (i know its sounds contradictory lmao) stuff is only possible because the mc is the son of apparently (one of) the most powerful being(s). So far it looks like Castiel (his angel father) is the one of the seven divines, the gods above the gods and somehow even able to give orders to the other divines.
Only because of that the MC (the two goddesses helping him out for a eliza solution are his aunt and somewhat of a foster-mom) receives the help to turn Eliza into what she is now.
So yeah it is a dbz powerup BUT there is some reason and lore involved which makes it fair game and the mc needs battle companions. Mc, Eliza, Rin and Luna is a pretty good start for that.
And still, nobody is as powerful as the MC (will be) apparently, maybe not even the divines and gods (or they cant interfere), lets see what Balthazar brings to the table.