My rational mind is thinking "Oh, the MODERN MILITARY guy used to GUNS and not SWORDS is dogshit in SWORD FIGHTS" but at the same time, in an earlier chapter, MC said there was no time to rest, only Raids and battles. So... I know you can't really learn this kind of stuff in 2 weeks but if the og owner is considered an amazing sword woman, wouldn't you have some remnant of muscle memory? Not asking you to be reborn swordmaster out of the bat, but still...
Even then, it's just an underwhelming MC with a survival instinct.