From Memory Alpha, the free Star Trek reference
The
nisroh is a bladed
weapon used by
Tilonian merchants in the traditional bartering ceremony. In the ceremony, the merchant ceremonially wields the nisroh and is judged on his proficiency with the blade. Before his undercover assignment on
Tilonus IV in
2369,
Commander William Riker was briefed on the use of a nisroh by
Worf, who accidentally cut him on the forehead. The wound became a focal point of the delusions manufactured by Riker's mind when he was resisting
interrogation by the Tilonians. (
TNG: "
Frame of Mind")
