IS BORROWED FROM
THE ANCIENT SWORDSMITHS OF JAPAN.
A BLADE MUST BE MADE OF HIGH CARBON STEEL
TO HOLD A KEEN EDGE
BUT A BLADE MUST ALSO BE SOMEWHAT FLEXIBLE
OR IT MAY SHATTER IN COMBAT.
THIS REQUIRES MILDER STEEL.
A TRADITIONAL JAPANESE SWORD
IS MADE OF BOTH METALS.
TWO DISSIMILAR STEEL BLANKS
ARE FORGED INTO THE RAW BLADE,
WHICH IS REPEATEDLY FOLDED IN HALF
AND THEN POUNDED OUT TO ITS TRUE LENGTH
UNTIL PERFECT.
THIS TAKES MUCH MORE THAN FOUR DAYS
WITH LITTLE FOOD OR SLEEP.