Staff is a multi purpose weapon really. Things like daze in chaos storm and the boons you get from Chaos Armor are two skills that are going to be good regardless of the build. Phase retreat is also a good combo with Chaos Storm for more protection/regeneration. Sure staff does conditions and they won't do as much as they would with a condition build but they still hurt. I also find the clones from Staff way more useful then clones from most other weapons as:
They are easy to make with Phase Retreats low cooldown and they give you boons and conditions. The boons are underrated by alot of players... the might from the weapon switch also helps this as its going to improve both my condition and power damage. Add in some boons from winds of chaos and some extra damage from conditions it does quite a few things.
Also one of the biggest aspects is I like Ranged Phantasms as they don't die nearly as quick. IDualist is one of them. IWarlock is strong in a power build. It does its damage based off power so it hits hard even when the enemy has few to none conditions. Add in conditions to the mix and its hitting even harder.
It hits 10% harder for each condition on an enemy. If you get a few conditions off on an enemy its going to hurt since the base is off power still and you're adding 10/20/30% damage to that.
Its just a good weapon in almost any build its defensive the clones do well and the Illusion hits hard.
Greatsword is strong for power builds as well as it does good damage but I don't care for the phantasm as much. Its on the lower end of the damage scale. The upside to it is that its AOE and cripples. I just find the staff Warlock more useful as I like to single target more then AOE.
Hopefully that helps.
I feel Scepter and Greatsword are still excellent choices for another weapon.
Also, remember vuln is one of the conditions we apply with staff which helps our power out as well. The rest is just extra damage.
Edited by Zorian51, 24 August 2012 - 05:24 PM.