Current understanding of the Ninjas and Samurai of ancient Japan usually equates them as being almost interchangeable masters of swordplay and other forms of combat; but the fact is that they were different breeds of warriors who used different swords. The Samurai swords were the best that the current sword making technology could produce and were made of the best steel by a select group of blacksmiths who were experts at making them. These superbly balanced swords with edges so sharp they could easily sever limbs even through armor were available only the Samurai class of warriors and less respected Ninjas were not allowed to use them.
Having a sword that was in some ways inferior to the Samurai ones did not make much difference to the Ninja and it was their special Ninja swords that suited them best. While Samurai swords were between 30 to 36 inches long, the Ninja swords were shorter at around 24 inches and they were also made from steel of lower quality. The Ninja sword was not used for cutting and slashing like the Samurai sword, but as a stabbing weapon.
This made the shorter length easier to handle and the fact that little cutting and slashing was done meant that there was no need to use had to find high quality steel to ensure that the cutting edge remained sharp for a long time for the Ninja it was the sharpness of the tip of his sword that mattered. Whether the evolution of the less sophisticated cheaper short sword of the Ninja and the development of a special form of fighting the makes best use of this weapon was a result of the economic limitations of the Ninja or the sword was natural outcome of their close quarter guerilla style of fighting is not known. The fact remains that although technically inferior to the Samurai sword, the Ninja sword was a very deadly weapon that was used to great effect in the distinctive guerilla style of fighting the Ninja were famous for the samurai sword would have been totally unsuitable for this.
There are many legends and myths about the Ninja sword and, knowing the innovative techniques the Ninja used, quite a few of them may be true like the one about the scabbards being longer than the swords to leave space to hide other small weapons. Another interesting story is that the short strong blades could be jammed into the ground and the Ninja could then stand on the handle to get extra height for getting over obstacles. In interesting story is that the tips of Ninja scabbards were removable so they could be used as snorkels when needed. Irrespective of the truth of these and other stories, the fact is that the Ninja sword was the perfect weapon for these deadly warriors.