Steel Skin

Steel Skin is a form of physical conditioning undergone by Samurai and, to some extent, Shinobi, albeit the latter utilize chakra flow to achieve similar effects. By constantly exposing the skin to the sharpness of a blade over numerous years, along with training it to become resilient to virtually all impacts through muscle enhancement, one's skin may become as "strong as steel." While this isn't literally the case, their skin becomes much harder to penetrate through ordinary blades and strikes, making it a highly viable method to use against strict kenjutsu practitioners when one does not have a weapon, as would be the case for some Samurai.