Sword of Kahless.
The first bat'leth forged by Kahless the Unforgettable around fifteen hundred years ago. In the centuries following Kahless's death, the sword became a sacred icon of the Klingon people, until it was taken by the Hur'q about one thousand years ago during their invasion of the Klingon Homeworld. The Sword of Kahless had been wrapped in a cloth that also became a revered object. After the disapearance of the sword, numerous fakes of the Shroud of the Sword emerged over the centuries. The true shroud was discovered by a Vulcan geological team, inspiring Dahar Master Kor to enlish the help of Jadzia Dax and Worf to set out on a quest for the legendary artifact in 2372. ("The Sword of Kahless (DS9)." Kor, Worf and Dax actually found the Sword of Kahless on a Hur'q planet in the Gamma Quadrant. Fearing that the sword would only serve to divide the Klingon Empire, they decided not to reveal its discovery. They left the ancient bat'leth floating somehwere in free space, perhaps to be found in another thousand years. This entry reflects their wish that the sword remains lost for the time being.

- Star Trek Encyclopedia