Inazuman smiths spend years working on a single katana and fold it up to a million times to produce the finest blades known to Teyvat.
Katanas are thrice as sharp as Mondstadt swords and thrice as hard for that matter too. Anything a longsword can cut through, a katana can cut through better. I'm pretty sure a katana could easily bisect lawachurl in its armor with a simple vertical slash.
Ever wonder why Abyss never bothered conquering Inazuma? That's right, they were too scared to fight the disciplined Samurai and their katananosabitonareeee. Even in Archon War, enemy troops targeted the men with the katanas first because their killing power was feared and respected.
So what am I saying? Katanas are simply the best sword that the world of Genshin has ever seen, and thus, require better stats in the game, such as +200% Crit damage as a passive ability.