Masamune was a legendary swordsmith in ancient Japan...
if his katanas still exist, they would be national
treasures..
the swords are curved because of 2 types of metals beaten into a
blade... the hard and brittle steel for the cutting edge and the
soft and malleable steel behind for strength and
flexibility...
with that, they had the best of both worlds.. a hard cutting edge
and a strong blade which will not shatter easily 