True. Luke told Kyle no one should face Desann alone, including himself. He said: "Now that Desann has been to the Valley, there's no telling how powerful he's become." Further, we don't know how long they've been fighting. Because he was laughing, Desann likely wasn't even using all his power, toying with his so-to-speak. Similar to Dooku's one-sided battle with AotC Obi-Wan. Luke wasn't an idiot, and if he could help it, made it pretty clear that he would have run away instead of fighting him. He told Kyle that he was forced into it-never even felt him comming. The only person we know he was going all-out on was kyle katarn.