I do listen to stories... but believing in it is another. While researching, one can hear many kinds of stories. Stories like these are rampant. There's even a book "Esoteri Keris", (in Bahasa Indonesia), which forewarned about these trickery.
To me, even if it's a "powerful keris", it's no point having it without knowledge of its use. It's like having a machine gun, but don't know how to load the cartridge and fire the weapon. It's meaningless.
To each their own. Thanks for the story.