It has a special attack called From the Shadows: a wight is summoned from the Shadow Realm that attacks your target five times, dealing 20-100% ability damage each attack. This costs 50% adrenaline, and only one wight can be summoned at once.
Weapon gizmos charged with perks can be used to enhance the weapon's abilities. As a two-handed item, the augmented Staff of Sliske can hold 2 gizmos, allowing up to 4 perks (2 perks each).
Using this weapon in combat can gain experience to increase its level. Levelling the weapon will have no effect on its ability in combat, but it will improve the experience and materials gained for disassembling it.
The Augmented Staff of Sliske uses charges stored in the universal charge pack. When the charge pack runs out of charges, the item loses stats and gizmo effects, and can also no longer gain any equipment experience. Function will resume when the pack is recharged with divine charges.
Your current drain rate for a tier 92 two-handed weapon is given by the following table. It depends on your current reduction researched, the item level, and Efficient/Enhanced Efficient perk presence.