Japanese swords are probably the most popularized sword in history. This
is most likely in part to the cultural significance that both the sword
and the military had in Japan. In fact during the height of the Chinese
power (the Chinese were notoriously xenophobic and believed in their innate
superiority in all things) they reportedly imported Japanese swords for
their army. Sword making was elevated to near religious status in Japan.
The 3 Japanese blades that were in the widest use were the katana (longsword),
wazikashi (shortsword) and the tanto (knife). These swords were made using
techniques that are still in use today. Incredible steel strength was obtained
by folding the steel literally thousands of times. This also gave the swords
an exceptional edge retention (stayed sharp). Also this process leaves a
distinct temper line known as the "o-midare" or turbulent sea which describes
the wavy temper line.