If you are referring to the fight on Coruscant, the goal was not to beat Jacen. The goal was to make it look like an assassination attempt and plant a tracking device on him. Kyle was not out to kill him. You can't use this as an example.
One word: Vaapad. Katarn has nothing for Vaapad.
If someone needs more convincing, lets do a quick comparison. Windu defeated the most powerful sith lord in history (Sidious) in a lightsaber duel. Katarn was defeated by Darth Cadeous when Katarn had not only ambushed Cadeous but also had another master and several knights with him.