I think you have to differentiate it from withches, I will propose the following for each.
Witch: cloth weave. Weapons : staff, wand, orbs
Necromancer; mail armor. Weapons: scythes, tomes, sword.
I think mail armor is better than cloth because I would like to see a mele specialization, similar to the death knight of wow, but only dps no tank
Scythes, glowing skulls, orbs or a corrupted staff.
Two hands: Scythe
or
main hand: dagger, off hand: skull.
I too like the idea of an orb as an off hand relic but rather it swirls with the captured souls of the Necro's victims. Set attacks would fill the orb and then be used in attacks while the main hand wilds a bone wand or dagger of the dead. Both to keep with the whole death/soul sucking abilities of the Necormancer. A Necromancer is never alone when they can raise the dead ;)
I would like weapons such as
* skulls / orbs / amulets
* staffs made of bones / eyeballs of the fallen / crystals / dark matter
* scythe / sickle (dual wielding)
* body parts (like severed arms or legs, human or monsters, be cool if it came from slain mobs)