According to Klingon mythology, the Klingon Kahless created the bat'leth around 625 A.D. he formed the blade by dropping a length of his hair into some lava from inside the Kri'stak Volcano, then cooling, shaping, and hardening it in the lake of Lursor.
He then united Qo'noS, the Klingon homeworld by killing a tyrant named Molor with the weapon, which became known as the "Sword of Kahless". The sword was later stolen by a species called the Hur'q during their invasion of Qo'noS. Worf and another Klingon named Kor rediscover the artifact, but it is eventually transported into space to prevent them from using it to attack each other.
The Sword of Kahless differs from normal bat'leths as it has five points and one handhold compared to four points and three handholds.
In the Klingon language, the bat'leth was originally referred to as batlh'etlh, then was shortened to betleH. The word "bat'leth" means "Sword of Honor". Bat'leths are made of a reinforced metal called baakonite and are normally 116 centimetres (3.81 ft) long and weigh 5.3 kilograms (12 lb).