One of the popular legends is that Amakuni and his son Amakura were standing outside their sword smithing shop when the army was returning from battle. As a sword maker to the Emperor's army Amakuni was expecting to be acknowledged by the Emperor, as had been the norm in the past. However, in this case he was snubbed by the Emperor and soon understood why when he saw many of the sword blades carried by the soldiers were broken. He was determined to research and build the perfect sword.

After a period of sabbatical and reflection, Amakuni and his son went about developing a superior weapon. The next summer when the Emperor returned from another battle, none of the swords were broken and the Emperor passed and said to Amakuni, "you are an expert sword maker, none of the swords you made failed in battle". What Amakuni is said to have developed is a style of sword that was hard enough to hold an edge but flexible enough not to break or shatter, the paradoxical combination needed for a good blade.

The Japanese did this by creating a sword from two different types of metal. The core was made of steel with a high carbon content.This makes the steel very hard but very brittle. Folding it over itself over and over again to create steel with up to 30,000 laminations strengthened this hard core. Around this hard core, softer and more flexible steel was wrapped. The two steel were welded together and the edge was tempered (tempering created the Hamon on the blade). The end result was a blade with exceptional edge holding and cutting ability. And with the flexibility to withstand continuous contact with other weapons or armour on the battlefield. This is how the unique nature and shape of the Japanese blade is believed to have been created

The myth of blood grooves.

Why do blades have blood grooves? Answer: - to allow air or blood to escape from a STABBING attack because it will enable you to with draw the blade from the body.

However the samurai sword was made to cut or slash not stab. So what are these grooves for ?

Answer: - The grooves (hi) exist for 2 reasons.

1) To reduce the weight on the heaver blades making them easy to deploy. By using this method the balance was undamaged.

2) Grooves were also used to cut defects out of the blade occurring from the forging process. This could happen to the best sword smith on occasion.