"The" Katana

Through trading with the outside word, the wester tribe of "nishi no hito" has aquired different metal tools as well as spears with metal tips, but only recently have they gotten hold of a masterfully forged katana. Allthough more spears would have been more effective for battle, the katana is very impressive and serves as a symbol.
When reaching out to a new tribe in order to initiate trade, the leader of the "nishi no hito" demonstrades and sometimes holds it high during a speech, in order to impress the other tribe. But this method can be a double edged sword,(even though it is a katana with only one edge) since some of the mre pridefull tribes deeply submerged in the forerst, do not like being practicly forced into having a relationship with another tribe, while being held at gunpint (or swordpoint). Over a long period of time this will surely be frustrating for the pride drdiven clan and there is no telling how they would respond once they had enough.
But they were only sold the weapon not the axct methods of how to treat and preserve it. Over the weeks there aer already some slight signs of rust and small notches on the blade. For the untrained eye something like would be hardly visible but a person of knoledge would see that this can't go on forever.
The existense of the blade doesn't just make other tribes nervous, but also the chief who owns it. He can sometimes get paranoid about other people trying to steal it. This paranoia makes him angry at disobedients and he doesn't allow anyone, especially lower reanked tribes members to get enyqhere near his blade. That would be difficult anyway because he constantly wears it at his side.