All things considered, pure swordsmanship shouldn't be Shin's forte. He's an adventurer, after all, being a player of an open world fantasy RPG. Though he certainly does greatly emphasize sword fighting in combat. But if he had fought now like the needed to fight against the ultimate last boss of the death game, how many seconds would Munechika have lasted?
IIRC Munechika was a end game event RAID BOSS and wiped the floor with everyone, Shin included.
Shin is stronger then her, but Munechika is probably kinda close to Origin as Origin was a 1 man boss.
Her stats are close to what Shin had before he got 2x stats from fighting Origin.
We do not know Origin stats.
Munechika has all around 900 , other then int which is 200 or so.
While Shin has around 2000 after 2x stats in all stats.
Level 255 is the max for players, but when you hit it, you could reset your lvl for a stats boost.
The reincarnation system that allowed people to reset their stats is going haywire.
This is also why "Chosen ones" who are born with skills, tittles or alot of stats exist.
Even if he was mainly known for being the best blacksmith in the game.
Shin is still pretty good at fighting hand to hand as a max level Samurai.
Shin is able to fight her on even ground thanks to his buff from the final boss giving him 2x stats.
And the fact they are not using any crazy magic moves.
But in pure skill, Munechika is probably one of the best in the world.