My paladin has this ability but apprantly SOE have taken out the quest for it and are going to revamp the whole story line. You started the quest for this in Misthaven Crossing as you fight vampires there. You would do the quests and there was a slight chance of during one of the fights would get bitten by one of the vampires.

 Then Kip a halfling vampire slayer would explain who would need to see to cure it. Or keep it. If you cured it the reward was a fairy pet that was disabled due to it being able to one hit kill everything in the game. The other side of the quest was you went completly the other way and became a vampire. This gives you a 6 minuet levitate spell only at night time but it changes you into a bat form.

And yes the bat form is still in the game as I was flying round Tursh the other day  But the quest is disabled and the unlock for the quest is removed.