Originally Posted by
croana
Keep in mind that the tenticles hit for a LOT harder in unholy than in frost, because the tenticle's damage scale with unholy's mastery. The reason you might be finding that unholy is underperforming for your gear at the moment, I assume, is because you aren't reforged correctly. This weapon requires you to reforge as much crit into mastery as you can, and then you'll find you're getting higher dps numbers. Of course, this also assumes you aren't just auto attacking the dummy and seeing what happens. A big portion of unholy's damage continues to be from your (empowered!) pet.
Pretty much, this weapon is tailor-made for unholy. Your recorded lower dps probably has more to do with poorly reforged gear and bad playstyle.