This chapter is the moment I see him becoming OP. Also, he could go back to Galliad, give him the pendant, then rest and cultivate his magic in that safe place for the next 15 hours.
But no, let's just kill all the monsters!
and that ending. pleasure cultivate in a safe place... hrmm... lets see, middle of 3-way battlefield with soldiers still alive and ready to kill anyone/thing?... perfect.