They were Bardiches, carried by Ophidian Berserkers. They had Terathan and Ophidian slayers on them. They also had the same ability to damage the Ophidian Berserkers, and later the Daemon Berserkers that Mystic weapons did.
However, their usefulness in the Ophidian War was limited, because the presence of Terathan slayer on the weapon caused all Ophidians, including the Berserkers, to do extra damage to their wielder.
Inavlis's Burchete was a rarer form of this weapon.