So I put Whirlwind on the primary function for the Death Knight and sent him into a group of enemies. It looked as if the only time he did damage was when he'd do a normal attack - every time he spun around it did nothing. What's going on?

Nevermind - looks like it does an extremely low percentage of normal damage per whirl... I guess there's a skill or something to raise that, but for now it's uselless unless mobbed by level 1 rates...