You can often find a widespread opinion that the Japanese katana is the summit, the Everest of blacksmithing. There are phenomenal myths about its properties, such as, for example, that a katana made by the hand of a master is so sharp that it can cut a warrior in plastic armor in half. Alas, this is contrary to the laws of physics, at least if we talk about a medieval samurai sword. What myths exist about this samurai weapon?
First, the katana is not a samurai weapon; in Japan, even the last peasants wore it. It was not the prerogative of the military elite, by no means. Here we are talking about a bunch of katana and wakizashi (short sword), which showed the status of the owner and that's it. Second, the quality of steel in Japan before the arrival of Europeans was, frankly, worthless. Research has shown that the Celts of the 5th century BC. possessed approximately the same sword-forging technologies as the Japanese during the Edo era.
As mentioned above, the quality of Japanese steel was low. At the first meeting of the Portuguese and Japanese pirates, the samurai simply could not break through the European steel, and this is not counting the firearms. Steel in Europe at that time was many times and many times better than Japanese, this is noted by both the Japanese themselves and the Europeans. Often katanas naturally broke in battle, even the modern katana in the Mythbusters experiment broke when hit by another katana. So, tales about the legendary samurai swords are nothing more than fairy tales.