The Byzantine Parang is a supernatural weapon and an object in the TV series Sleepy Hollow. It causes its wielder to act on their darker impulses and soon be overcome with an unquenchable bloodlust. It was held by various people in England, all of whom Ichabod discovered to be the infamous killer, "Jack the Ripper".
The weapon is believed to have been made in the Byzantine (Eastern Roman) Empire around the early 11th century for Iftikhar al-Dawla, Fatimid governor of Jerusalem during the siege of 1099. A legend states that anyone who wields the Byzantine parang would be overcome with a bloodlust to kill anyone they hate.
Pandora's next assault involves giving a man the knife that causes him to act on his darker impulses and murder those he hates. Witnessing one of the bodies, Ichabod recalls a similar case when he was a boy at Eton College in 1763, and realizes that the killer they are tracking was also Jack the Ripper. Research at the archive reveals that the Ripper's knife is the actual Ripper, as it drives its 'wielder' to kill.
Researching the past killings, Ichabod and Abbie realize that the killings are always stopped amid a wave of disease, realizing that the knife absorbs the blood of its victims and its wielder died when the knife killed someone with the disease. Although attempts to shoot the killer with malaria-tainted blood failed, Ichabod is able to defeat the possessed killer by infecting himself with the disease, which he had already built up an immunity against.