Why do so many people said that Katana is the Best sword ?

You have too much freetime.

 

I've been enjoying this thread.

I like the point koyo made about the status of the katana within Japanese culture and how this might have led to the perpetuation of the idea that the katana is the 'best sword'.

European weaponry is much more vast and the geographical area and variety of weaponry probably means no one weapon stood out in the same way the katana did. However this by NO means makes the katana the best sword or best weapon. The hands that wield a weapon are equally important.

 

As usual Koyo is on target ... No weapon hung around europe long enough to gain such a standing that the katana did. Take the longsword as an example ... it appeared in 1250 ish, evolved several times and lasted till 1650 albeit as a 'sports' weapon. However as soon as it had outlived its usefulness on the battlefield it was discarded. Such a fate did not befall the katana.

 

There were other koryu out there prior to Katori Shinto-ryu, such as Nen-ryu, Chujo-ryu, Toda-ryu & Kurama-den bujutsu (Not Kurama-ryu), but they are no longer extant and have left no trace of their historical documentation. These were the primordial forerunners for the more reconized schools of kenjutsu. It's possible to surmise that they might have had two sword technique.