(covers information from several alternate timelines)
The bat'leth competition was a Klingon tournament held on Forcas III. The competition was fought with bat'leths. The tournament was often violent and led to many participants being maimed and severely injured.
On stardate 47391.2, Worf returned from the tournament with the first place trophy, Champion Standing. In another quantum reality, he placed ninth, while in another, he was unable to attend the competition altogether. (TNG: "Parallels")