It was nothing but the emperors of Japan in the history of itself which brought the formation, production and imagined uses of the samurai sword in the beginning of the Japanese history. Nothing seemed to be impossible for the Samurai warriors that were solely responsible for the popularity of samurai sword. It is felt that the samurai warriors had origins in 8th or 9th century at the time when Hein Periods was ruling the concerned region. In the beginning, the warriors used the bows, arrows and horseback as their weapons primarily in the wars. With the passage of time, the warriors evolved with their own ethical code known to be Bushido. But, to the contrary they were defeated by the Mongols which compelled them to revaluate and revise their weapons and other fighting equipments. This was the time for the samurai warriors when they adopted the samurai sword as their main warfare equipment in most of the coming wars. If you want to know more about this, check out Samurai Sword.
As per the historical data reveals, it was the name Daisho that was given to the two swords which were carried by every samurai. In other words, it was treated as the warriors' soul. The longer one was made of the primary fighting blade called the Katana Sword and the second one which was smaller could be called as Wakizashi sword. The relationship was so strong between the warriors and the samurai sword that it was considered that the outcome of the forging wars would be totally depending on the infused battle by these two swords. According to the warrior tradition, a person aged thirteen could be given Wakizashi blade and a young name that profoundly welcomed him into the samurai community. Katana sword was later given to home at the elder age so that he could participate in wars.
The anticipation and the strength of relation between the two could be easily understood by the fact that the samurai has to carry the samurai sword till his death. The saying goes that the samurai warrior would rather die in the battle field carrying his Samurai Sword or he will commit the traditional samurai suicide known to be Seppuki at his own hand. For more info, visit this link.