In FFX there are 3 names mentioned that i heard some people discuessing over and there significance. Masamune, Murasame, and Muramasa. I asked my old Martial Arts intructor from japan about it and he said that Masamune WAS supposidly the best spirit smith(sword smith) in his time, rivaled by Murasame(basically Masamune was a good smith and murasame was a bad one, yin yang kinda deal.) Masamune was from the soul and always carried you through battle, while murasames thirsted for blood and could "cut through an iron helmet like it wasn't there."(not verbatum, but close enough) Supposidly after battle, Murasames sword thirsted so much that they would betray their wielder and kill them. The way you could tell who made which sword was to put the sword, blade pointing up stream in a creek river, what have you. Dropping a leaf in the water up stream. If the leaf moved away from the blade, it was made by Masamune. If the lead was seemingly drawn to the blade and cut in two, it was made by Murasame. He didn't remember the name Muramasa(But comon, he is old, give him a break) Just thought you guys MAY have wanted to know that.
