Well Moorgard admitted to it on the SoE forums so I guess you're just a naturally fast runner or you got a lame horse.
This is what he said in a thread of people complaining about it.
Quote:
Moorgard wrote:
We explained up front that these spells were meant for nothing more than flavor and fun. Since fun is an entirely subjective term, it's difficult to please everyone.
It was not intended that the horse spell that paladins and shadowknights receive would have a speed buff, but due to an error on our part it does. It's a slight speed increase compared to other mounts, but it exists nonetheless. Our options at this point are:
Nerf the speed buff on the flavor horses so they provide no actual benefit.
Spend development time trying to think up marginally useful spells for all subclasses. Then come up with another round of these abilities when people complain that a different class has one that is somewhat more useful than their own.
Do nothing.
We have chosen the third option at this time. The effect of the horses is not such that it gives knights a game-imbalancing advantage, and we see no benefit in taking a minor perk away from a couple classes just to satisfy someone else.
So yes, knights get a flavor spell that is actually useful, and other subclasses don't. The flavor spells are a relatively minor element of gameplay, and we don't plan to modify them at this time. Now I'm not complaining about it myself. I'm just saying that if that is their attitude to what they admit to be an error on their part then I don't think they are going to be changing the booko scribing error in an awful hurry either.