| Combination of trial and error and utilizing any metallurgical advances brought to Japan through intermittent contact with the rest of the world. Actually, Masamune's era is considered to be the height of Japanese bladesmithing. The nation currently believes that something has been lost to the artists at some point. (This statement is made as of the 1980s. Some of this may have been reclaimed since then.)
The use of higher quality steel makes up for this in the quality of the blades, but it is an art in Japan, not a science, so loss of knowledge/ability cannot be completely be atoned for by better materials. |