We have no idea how Kyle won against Desann either as it's entirely a matter of gameplay for their duel. As I recall, the player has the means to to get amped and become temporarily invincible during the fight, thus it's possible that Desann > Kyle and that Kyle winning is no different than Obiwans victory over Darth Maul in TPM.
There's certainly nothing to indicate that Desann is above or equal to Luke, but there is plenty to indicate that he's not a joke or bantha fodder as people seem to like suggesting. Luke tells Kyle that they should not take him alone and also explains that the only reason he took him on alone was because Desann came out of nowhere. All in all, a very impressive showing and we'll leave it at that.