The hardening process does not cause the curve, that is forged in as the edge is drawn down, the edge hardening
process does cause the different temper lines, spots and
other distinctive signs of the hardening process, the use
of refractive clay coatings, slows the hardening process
away from the edge and allows the back to be springy and
tough.
Many men were killed by a bokken.
Musashi fought several duels bokken against Katana,
once carving a bokken from an oar on the way to a
fight on an island.
It is very hard to find good swords cheaply now days, but
one does run across them, I have a showa blade I took in trade for some blacksmith work, I made a wrought Sai for a martial arts instructor.
It is lacking a handle and I 'm looking for a shurasaya
or white wood scabbard for it.
The handle is inscribed with the Showa stamp and an inscription, also shows the file strokes which help to
identify a real blade.
The great blades were sometimes made up of up to FIVE different types of steel, with the hardest being the blade
edge, the softest the center, slabs of medium on the sides
and a bit harder on the back.
I experimented with forged blades in my youth, and developed
a process similar to the japanese, for making tantos and
other small blades with temper lines and hardened edges.
Musashi's opponent threw his saya into the waves to show that there was no turning back from this fight. Musashi replied something like "you must have no confidence in yourself, since you don't think you'll get to sheath your sword". Then Musashi killed him with a bokken.