Jean Hag said:
A katana made from a master smith.
So sharp it can cut a piece of paper dropped on it, or more practically, cut a man in two, right shoulder to left belly in a single swing.
I wanna see any european sword make that.
Bigger European swords didn't need to cut through anything.
The sheer amount of force that could be put into a swing would crush and cleave through anyone unlucky enough to get in it's way.
If a Samurai were to fight a European Knight, the Samurai would lose every time.
The katana is not a blocking weapon, and a shield was not used with it, that pretty much puts the Samurai at a huge disadvantage already.
Even if the knight forgoes the use of a shield, many European swords are sturdy enough to block attacks with, and very capable of blocking a blade as fragile as a katana.
Then we've got armour. Samurai armour is made from the same crappy metal as their swords, while a knight wears armour that a katana wouldn't stand a chance in hell of cutting through.
I like katanas, I like the way they look.
But they're really bad swords.