Psionic resonator

From Memory Alpha, the free Star Trek reference

A psionic resonator is a type of weapon that functions by amplifying telepathic energy and focusing it into kinetic form; as such, the destructive power of psionic resonators is greatly disproportionate to their size and the energy required to operate them. However, the difficulty of controlling such weapons is not insignificant and they can easily malfunction, causing damage to their wielder.

In 2369 one type of Vulcan psionic resonator, known as the Stone of Gol was discovered to still exist, though in pieces, long after it was thought destroyed. The mercenary Arctus Baran was hired to locate the pieces and deliver them to the Vulcan Isolationist Movement (TNG: "Gambit, Part I", "Gambit, Part II")

According to the Star Trek: The Next Generation Companion, the weapon was much more powerful in early drafts of the episode; it was able to kill millions at a time.