Some smaller points. Daikatana: means really big katana! Nope. There was a game called Daikatana. It is just a horrible translation of Japanese Kanji. DAI is japanese for big. DIATO is japanese for "big sword", also known as a "katana". DAIKATANA would mean "big big sword" which is horrible grammar in Japanese. No-Dachi or more correctly Odachi are the very large katanas meant for battle. Why is the edge of a Japanese katana so sharp? Well, it has nothing to do with the curve or the hamon. The swords are polished, rather expensively might I add, to be razor sharp. Not all blades are sharpened to the same exact cutting edge, a thicker edge may be left on a sword that will experience heavy armor or very heavy cutting, but a razors edge could be used on an unarmored opponent. Since the katana was more of a deuling sword than a weapon of battle, a Samurai could have his sword polished to a razor edge because his opponent would be wearing only a silk kimono.