The Knife of Kirom was a legendary Klingon artifact that was over a thousand years old and had an important place within the Klingon Empire as it was stained with the blood of Kahless the Unforgettable. Due to this, it was kept within a sacred vault on Qo'noS where no one was allowed to enter.
Gowron, the Chancellor of the High Council of the Klingon Empire, used the Knife of Kirom to run a genetic analysis on the clone of Kahless in 2369. (TNG episode: "Rightful Heir")
In 2376, Neelix recounted that the knife was unearthed by Sarpek the Fearless while he was searching for his lost targ. (VOY episode: "Barge of the Dead")