In Celtic mythology, it is said that the ancient swords were capable of speech. Whenever the sword was pulled out of its scabbard it would sing out the full history of all its deeds, because (according to the much later Christian chroniclers) there was a demon in the blade. Cleaning the sword was seen as an act of tribute or religious worship to the spirit in the sword. These legends are remarkably similar to Indonesian and Malaysian beliefs about the “kris” or “keris.”
The kris is the traditional sword or knife (depending on its length) of the peoples of Indonesia and Malaysia. While the kris is a weapon, it is at least as much a ritual object, because it is designed in such a way as to be not very easy to fight with it. The typical kris has a wavy blade and an offset handle. It is worn as a symbol of manhood, but some kris are also “charged,” filled up with magic power and possessed of special powers such as the ability to warn of approaching danger by shaking or rattling. Some Indonesians even conduct rituals to pay respect to the kris, seeing it as a living being.
If you go to Indonesia, it's not too difficult to buy a “magic kris,” but those are just tourist trap souvenirs. If the owner believed his kris to have genuine power, he wouldn't sell it for less than about twenty thousand dollars. The kris is taken very seriously!