Oh wow, what a waste of time this turned out to be, In the first chapter they set him up to be this ruthless soldier that kills every threat that comes his way, but just 20 chapters later he's having some moral dilemma over killing someone that is essentially this world's most evil existence, they literally kill people to experiment on their brains for godsake, and he's not instakilling her because he had 1 conversation with her once over the course of a couple months.
I could understand the blathering and indecisiveness in the first evil mage fight because the manga needed him to talk for exposition purposes that lead up to this fight, but now he's just screwing around letting her fully powerup for no good reason, why wouldn't he just cut her limbs off and then freeze the stumps if he didn't want to kill her. There are so many methods of incapacitating someone with his powers and he decides to lightly stab her in the leg, and then just assume she's out of commission.
It's so frustrating.