Shinobi (aka "Ninja" in modern, 20th century terms) actually used the short, straight blade Ninjato rather than the medium length, curved blade Katana, short, curved blade Wakizashi and straight blade Tanto knife which the Samurai used (Although the Shinobi could use a Tanto as a part of their large arsenal as well). The Samurai also used the long, curved blade Tachi.