It is like the Voynich Menuscript, nobody knows how this thing works and nobody knows how to use it effectively.

The Neuro-Disruptor is a weird, WEIRD weapon. Imagine a crystal that has been carved into a shape of a gun which resembles more like some Neckbeard's dollar store space gun that goes pew pew. Except these pew pew can cause erratic seizures and brain shutdowns. It functions similiar to that of the Neural Shredder but its mechanics are beyond alien. The Neuro-Disruptor is a psycho-crystalline weapon of unknown alien manufacture, used most commonly by the Eldar Harlequins. It is a handgun made of a transparent crystalline material, or more accurately someone stuck a rock onto an empty pistol frame and called it a day. Even the Orks would call this half-assed.

Upon closer examination, it is indeed literally a rock glued to a gun frame, as there are no power sources or mechanical parts within the gun, its fired soley by the mind of the user. Its essentially a quasi-magic wand in the shape of a gun, meant more as a conduit for the user's abilities, if said ability was confined to them lobotomizing targets at will, so its like a magic wand with a pre-set spell inside.

It uses intricate psycho-crystalline circuitry to emit a wave of particles that disrupt the brain's neural pathways. Armour offers no protection from the Neuro-disruptor and only those of mental fortitude (Read: a battle-hardened Psyker) could resist the affects of the Neuro-Disruptor.

For its more spooky counterpart, see here:

Weapons of the Eldar
Sidearms: Shuriken Pistol - Fusion Pistol - Neural Shredder - Neuro-Disruptor
Basic Weapons: Avenger Shuriken Catapult - Death Spinner - Eldar Flamer - Fusion Gun
Lasblaster - Laser Lance - Prism Rifle - Ranger Long Rifle - Reaper Launcher
Shuriken Catapult - Swooping Hawk Grenade Pack
Exarch Weapons: Dragon's Breath Flamer - Fire Pike - Hawk's Talon - Prism Blaster
Spinneret Rifle - Star Lance - Sunrifle - Tempest Launcher
Warp Weapons: D-Cannon - D-Scythe - Wraithcannon
Heavy Weapons: Bright Lance - Eldar Missile Launcher - Pack Grenade Launcher - Scatter Laser
Shadow Weaver - Shuriken Cannon - Starcannon - Suncannon - Vibro Cannon
Vehicle Weapons: Doomweaver - Phoenix Missile Launcher - Prism Cannon - Pulse Laser
Super Heavy Weapons: Psychic Lance - Pulsar - Revenant Missile Launcher - Sonic Lance
Melee Weapons: Diresword - Eldar Power Sword - Executioner - Ghostglaive - Mirrorsword
Scorpion Chainsword - Scorpion's Claw - Singing Spear - Witchblade
Miscellaneous Weapons
Grenades & Explosives Plasma Grenade - Haywire Grenade - Hallucinogen Grenade