The important role of Habaki
If you look at examples of traditional Japanese swords, you may notice that many of them have a ring at the bottom, which is a relatively small component, usually only 1 or 2 inches high, while completely enclosing the blade itself. When many people saw this piece of metal for the first time, they thought it was just an ornament. In feudal Japan, swordsmiths often added intricate decorations and ornaments to their swords, but this metal ring was actually functional.
The metal ring found at the bottom of traditional Japanese swords is called "habaki". It has been used in traditional Japanese swords for centuries, and its origin can be traced back to the Kamakura period in Japan. Historians generally agree that it serves two purposes, one of which is to secure the tsuba in place. To prevent accidental self-injury, swordsmiths added a tsuba to their swords. The tsuba, also made of metal, is a ring between the tsuka and the blade itself. Without a sword, a samurai or martial arts practitioner may be injured if his hand slips while swinging the sword. However, tsuba prevents this from happening by creating a barrier between the user's hand and the blade.
Another purpose of habaki is to prevent the sword from falling from the scabbard (saya). Most saya provide a close and safe fit for their swords. Since the habaki is slightly thicker than the blade, it allows samurai and martial arts practitioners to basically wedge their swords into their saya. When a samurai or martial arts practitioner draws a sword, they usually grab the sword with their thumbs and use enough strength to pull the sword out of the Saya.
The habaki is not a permanent part of Japanese swords. Instead, samurai and martial arts practitioners must remove it regularly for inspection and cleaning. About every few months, the habaki must be removed from the sword. After removal, the samurai or martial arts practitioner will apply oil to the inside and outside of the habaki to prevent it from rusting, corrosion and degradation.