When you are geared enough for heroic, the dagger also drops a lot too, I have it on all my shamans. I have the sword on all my locks and mages, both have about the same spell power but the dagger has mana regen on it instead of the crit of the sword (I think).
If you are running shamans the shield from Tyrannus is worth trying for too, it is ilevel 219 and can be farmed on regular PoS too.