This quest was marked obsolete by Blizzard and cannot be obtained or completed.
Wait for Menara Voidrender to complete the Orb of Dar'Orahil and then speak to her again.
Wait for Menara Voidrender to complete your item
I will get started immediately on crafting your orb and infusing your new demon into it. When done, you will have the choice of having it in the form of a staff or orb. I always felt it was important to cater to a warlock's chosen weapon... I see no reason not to continue that practice.