The guy takes down a minotaur of epic proportions. No big deal. (I may exaggerate a little here, but still.)
Taking a mission of subjugating goblins. Huge deal.
Seriously, the common sense in these manga-fantasy worlds is just completely off.
Ooooh now i understand....so he knows what's needed but not where the minimum is so he trained that for so long that he didn't realize that he's long passed the minimum
I got a hunch that MC great sword will evolving at later story. Got a new badass looks, able to absorb magic attacks, gives MC non-stop recovery (hp, mp, sp), and the most important thing the sword passively upgrade MC 'parry' into 'perfect counter'