A ninja sword refers to a type of weapon used by ninjas, who were ancient Japanese warriors known for their stealth and agility. It is a sharp and deadly weapon that they used for fighting and self-defense. Full definition
Wade's face and body are still scarred, and he still dispenses sanguinary rough justice, from behind his makeshift mask, with a pair of ninja swords sheathed in an X across his back. (nytimes.com)
There are a wealth of items which Naughty Bear can use as weapons, including an arsenal of guns, knives and sports equipment, along with some chapter themed weapons such as ninja swords and ray guns which are scattered around the level. (gamergeddon.com)
It will include a brand new character called Fu, who carries a ninja sword for swift attacks. (perfectly-nintendo.com)