Tachyon Arrow

You see that right here? This is what true pain feels like.

Also known as the Fuck-you-on Arrow, the Silver Assrape, Mister Pint-Sized Powerhouse, The Necron Proverbial Middle-Finger, The One-Punch Arrow, Strong Enough to Make an Exitus Rifle Look Limp, "I-Cannot-Believe-This-Puny-Thing-Has-More-Firepower-Than-Some-Titan-Weaponry!", etc, etc, yadda, yadda, yadda, you get the idea.

A Tachyon Arrow is an intricate Necron wrist-mounted directed energy weapon worn by Necron royalty like Necron Overlords, Necron Lords and Necron Destroyer Lords. When activated, it transmutes a sliver of inert metal into an unstoppable thunderbolt capable of piercing the heart of a mountain.

Such a weapon has near infinite range, and is able to penetrate almost any form of armor, including that of Titans. The only disadvantage to this astounding item is that its strange ammo supply is exhausted with a single shot, and is far too complex to be reloaded in the midst of combat.

If you have a need of a small, wrist mounted sidearm that can make Emperor Battle Titans bend over in shame, there are always the Necrons to have your back.

Weapons of the Necrons
Sidearms: Particle Caster - Tachyon Arrow - Transdimensional Beamer
Basic Weapons: Gauss Flayer - Tesla Carbine
Special Weapons: Gauntlet of Fire - Synaptic Disintegrator
Heavy Weapons: Gauss Blaster - Gauss Cannon - Heavy Gauss Cannon - Particle Beamer
Staff Weapons: Abyssal Staff - Aeonstave - Eldritch Lance - Rod of Covenant
Staff of Light - Staff of the Destroyer - Tremorstave - Voltaic Staff
Vehicle Weapons: Death Ray - Exile Cannon - Focused Death Ray - Gauss Exterminator - Gauss Flux Arc
Heat Cannon - Heat Ray - Particle Shredder - Tesla Cannon - Thermal Cutting Beam
Superheavy Weapons: Doomsday Cannon - Gauss Annihilator - Gauss Obliterator
Particle Whip - Tesla Destructor - Tesla Sphere - Synaptic Obliterator
Transdimensional Projector - Singularity Generator
Melee Weapons C'tan Phase Weapons - Hyperphase Sword - Voidblade