A katana is a japanese sword characterized by a curved, single-edged blade with a circular or squared guard and long grip to accommodate two hands. 

The katana is generally defined as the standard-sized, moderately curved Japanese sword with a blade length greater than 23.86 inches. It is characterized by its distinctive appearance: a curved, slender, single-edged blade with a circular or squared guard and long grip to accommodate two hands.

Western historians have said that the katana was among the finest cutting weapons in world military history.