From Destinypedia, the Destiny wiki
List of abilities:
The Hereafter: The sniper rifle Hereafter's first ability is that, when crouching, the zoom of the scope is increased. In addition, it becomes easier to aim when under fire.
Blinding Light: When a Precision kill is performed with this weapon it can potentially cause a flash of light that blinds and suppresses nearby enemies and opposing Guardians (As of the December update, this now activates for all precision kills). Opposing Guardians in the light lose the ability to look at their radar, thus limiting their depth perception and situational awareness.
Perfectionist: If an entire magazine is used, and every bullet hit was a precision kill, the magazine is refilled without losing reserve ammo.