Me and another Warlock guildmate just tested Fear in some duels, and the result is that Fear is pretty borked.
The maximum length we saw it last with DoT's applied was 8 seconds, and that was once (Fear, Rank 2 [15 seconds]). 8 seconds is roughly 2 applications of DoT's, and after the first time, they barely moved anywhere before it broke.
I'm thinking my Warlock is about to be turned into a Mule and Tradeskills horse.