Well, I watched a special on the History -or it might have been the Military Channel - and they compared a variety of swords in a variety of situations, and the katana came out on top... So that was the basis of where I was coming from.
At any rate I still would like a proper on in the game. The blades is a one handed sword,
Like so many things - it depends. The Katana was made as it was because Japanese ore svcked. European methods would have resulted in a horrible sword. The folding technique allowed the Japanese to create a very high quality sword from bad material. This is a compliment to Japanese sword makers, that they were able to do so much with what they had.
The Katana is arguably the best slicing sword ever made. Against the relatively soft targets it faced in Japan there is no sword better. Against heavily mailed mid-medieval European armor, not as good. Against late medieval plate - not good at all. Of course it never had to face late medieval plate, so historically it is a non issue.
In the game, however, it does have to face heavy plate armor. Well, in the game we can shoot fire from our finger tips, so why not a sword that can slice through plate armor

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Anyhoo - not trying say the game should conform to reality or that the Katana was not a good sword. Just that the facts are a bit more complicated than "best" and "worst" and IMHO make for a very interesting read.