And additionally while im a big fan of nephilim, some people really take the story too seriously.You see...I'm not a divine half-breed meant to face world-buster level threats. So I wouldn't need to do that. You are thinking from a rl perspective. I'm replying from the context of this game's story...
And it's not even assumption, the story itself has shown the fate of people he gets attached to. Parents murdered. Girlfriend crippled. His newer girlfriend would have been skewered by her own sister if the latter didn't have a, plot-induced, sudden change of conscience. His main opponent has already been shown to have a knack for targeting loved ones to get his way. He just saw it happening again with the witch mother.
Since he chose to surround himself with with others, he should take advantage of anything that can strengthen them. Otherwise he is just dragging the poor lambs to slaughter.
Its just the tone and everything is more like dragon ball than lord of the rings. The mc at this point is a half-angel super-saijan superman venom combination, whats the big deal about turning the main LI into something powerful too at this point.
The plot is closer to some anime power-fantasy, no need to be so butthurt about minor stuff, its just meant to be a fun ride.
Eliza, after all the training was barely able to fight off two goblins, its would be really annoying with her staying this weak all the time and the mc always having to safe her even from minor threats.