Many people buy will buy a katana sword for decoration but eventually become fascinated with sword play that they end up signing up for a martial arts class and make use of their sword.Among the 3 sizes of traditional samurai swords the katana has always been the most popular among collectors and martial artists alike. In addition to the katana sword there is also the Wakizashi, or short sword and then the tanto sword, about the size of a large knife.When choosing a katana sword there are a few.