According to popular saying, the samurai sword is not only extremely sharp, but also can easily win even it's against armor. But in fact, all weapons of the sword can't let people who wear iron armor blood splatter on the spot or even split in half with one swing through just like the movie and animation works shows.

We need to know that no matter what kind of armor is, it has a thick lining as a soft cushion to make sure the kinetic energy of the strike can be absorbed, rather than be transmitted to the body. Although iron armor needs toughness, which causes its hardness is slightly lower than the blade, but it is still made of steel after all, even it's a sharp samurai sword, it is impossible to split the armor or even split people who wear iron armor in half.

1. In Japanese history, there were also real incidents of samurai swords fighting iron armor

In the famous Ikedaya incident in Bakumatsu, ten members of the newly selected group put on Chainmail that the Japanese called "Roqku Ashi" to suddenly attack nearly thirty Sonnō-jōi warriors. As a result, none of the mission new group members was killed, and there were many good swordsmen among the Sonnō-jōi warriors and some of them even carried their famous family swords, but there were 7 people of them died and 11 people of them were seriously wounded, while the newly selected group fought more with less but no one was killed. Thus it can be seen that the Japanese sword does not have the properties of breaking armor for iron armors.

2. During the Japan Muromachi period, there was a popular type of samurai swords called "Gaisou"

The name sounds like it's an armor-busting knife that can pierce armor. In fact, the knife is usually worn on the right arm, which is used for thrusting with the left hand after drawing close to the enemy. It is not used for directly piercing the armor, but stabing the underarm, face, and other parts of the body that armor can't protect by a short knife instead. After all, as long as the armor can move, there have to leave space for the movement, and can't protect all sites of the body. In a word, this is a dagger specialized in sneak attacks on gaps.

In fact, the research shows that on a real battlefield, high quality battle ready katana is actually just a weapon, not the main battle weapon on the battlefield. Suzuki Shinya, a Japanese scholar, once counted the records of the "letter of military loyalty" used by 1729 warriors to report their battlefield achievements to their masters during the Sengoku period.

3. Samurai swords are really very sharp while against targets without armor

Japan has had the tradition of chopping a rolled up straw mat to test the cutting method and the sharpness of the sword all the time, because the Japanese believe that the density and feel of rolled up straw mats are very close to that of human limbs, they use straw mats as test objects to simulate chopping human bodies.

In the same way, many people now use pigs to test the cutting power of knives. In the test, samurai swords can even cut four pigs at once. These tests have proved that the cutting power of samurai swords to against targets without armor is beyond of doubt. However, this result also reveals that the main function of katana is not a weapon of war on the battlefield, but a weapon for daily self-defense and knife fighting.

So, rumors are just rumors after all, and the katana itself is just a weapon that represents Japanese culture. The appreciation of rational science is the true kingcraft.