Images: The Palace Guard

[David R]

I think part of it might be to do with the expected useful "life" of a blade in serious combat. The Japanese have a saying about this, "one battle or a thousand years". This is actually the thinking behind Samurai carrying two swords, during the Sengoku Jidai and early Edo they are nearly the same length, later they devolve to a long sword plus a much shorter blade. Even in later years, when they decided to "really go for it" they carried two blades of nearly the same length.