A Varon-T disruptor
The effect of a Varon-T disruptor
The Varon-T disruptor is a hand-held directed-energy weapon banned in the Federation due to its vicious nature: the disruptor literally tears the body apart from the inside out, resulting in a relatively slow and excruciating death. Only five were ever produced; four of them were owned by Zibalian trader Kivas Fajo and he slept with one of them under his pillow. Fajo used a Varon-T disruptor to kill Varria when she and Data attempted to escape his ship. (TNG: "The Most Toys")
Background
The prop used for the Varon-T disruptor was later used as a weapon in TNG: "The High Ground", "Captain's Holiday", "Starship Mine", "Gambit, Part I", "Gambit, Part II", and more, and VOY: "Fair Trade".
The weapon was shown as a phaser or similar weapon in "Gambit, Part I" and "Gambit, Part II". The weapon fired a momentary burst of blue in a beam and was used on stun by Picard and Riker. Even when set to kill, it did not cause the intensely painful death of a Varon-T disruptor. Also, at the end of that episode, T'Paal told Picard to "pick up the phaser." Even so, it is possible that Data recognized Fajo's disruptor as a Varon-T, despite only referring to it as simply a "disruptor." The Enterprise probably confiscated the four disruptors owned by Fajo, leaving only one unaccounted for, so it is extremely unlikely that the weapons in these episodes were Varon-T disruptors.