Well, the way I look at it, is that Obi-wan and Ulic will fight while Exar and Luke take on each other. After a tough battle, Luke will have beaten Exar and by that time, Obi-wan has used his incredible luck and resourcefulness to hold off Ulic. At this point, its Obi-wan and Luke versus Ulic, who goes down...
No, this a straight up duel so no Resourcefulness, and we're talking about someone (Exar) who was taught by Freedon Nadd, and walked into the capitol of his enemy during a war and walked into the Jedi Temple, froze all the Jedi Masters holding Ulic, and freed him. That is more than anyone else would ever be able to do. I believe Ulic was just below Exar, and Exar will hold out against Luke to give Ulic time to defeat Obi Wan, who was more rehearsed in the fighting of droids, and not powerful Sith. REMEBER: Exar and Ulic were Sith during a time of war where there was numerous Dark Jedi and Jedi. ROTS Obi lived in a world where a occassional Dark Jedi would pop up and the Dark Sider wouldn't be anywhere near the skill level of the average Jedi during Exar's time.