Ono (斧, also spelled "masa-kari") is the Japanese word for an "axe" or a "hatchet", and is used to describe various tools of similar structure. As with axes in other cultures, ono are sometimes employed as weapons. Many existing examples of this particular weapon are associated with the sōhei or yamabushi (warrior monks), who also adapt other agricultural tools as weapons although samurai are also pictured as using ono in wood block prints. Ono that were specifically designed for military use are of extreme rarity. The weapon version of the ono is described as having "a very large head with a very convex cutting edge and a large scroll-shaped peen opposite it. It has a sheath covering only the edge of the blade. The entire length is nearly six feet" (stone,475).
In Gameplay Edit
It's the weapon of choice or Barbarians and Barbarian Chiefs (only in Way of the Ninja and Tales of the Ninja), its design is very simple and primitive. In-game It shares some attack moves with katana-users but causes a slight bit more of damage, probably to compensate the barbarians' lack of defense.
See the Barbarian page for moveset.