Talon of Horus
The weapon takes the form of a large silver lighting claw with thumb blade and integral storm bolter that runs from the wrist to knuckles of the gauntlet. The ancient bolter fires to the same effect as a modern storm bolter. Two belts of ammunition are fed into the weapon from the right side and howling faces of daemons cover the casing ejectors.
Abaddon, after reclaiming Horus's body, took the claw for himself and uses it as a symbol of his authority.
It is assumed that the claw, used in conjunction with the daemon sword Drach'nyen, covers Abaddon's ranged abilities and confers the same benefits as a standard lightning claw.