appletonia
major studmuffin
It was only a young, inexperienced Ulic that was initially pushed back by Ommin's sorcery (which was so powerful that it put a legendary Jedi Master like Arca Jeth into a coma or something, as well as dominate the Force prodigy Nomi Sunrider and as Nephthys said, something like 7 Jedi at once), and the fact that he alone was able to ultimately resist it is a pretty great feat. Not to mention, sorcery can be harder to defend against than regular Force attacks, and didn't Dooku himself get easily dominated by Talzin's sorcery?
Ulic would later go on to become far more experienced and gain a Sith amulet, at which point he was capable of stalemating Exar Kun in a battle that would have lasted for hours, and was seen to be shimmering in the darkside in a comparable manner to Exar from the perspective of Aleema, both of which imply that Exar wasn't drastically more powerful than Ulic, and that he couldn't simply dominate him with the Force. And when it comes to feats, Exar vastly outstrips Dooku.
I see no reason to believe that Dooku is even close to as gifted a swordsman as Ulic is. People seem to find it impossibly difficult to admit that Ulic has, by far, the greatest demonstration of pure technical skill with a lightsaber there is, in fighting off a notable Jedi while having been cut off from the Force. Stalemating Exar Kun, himself a lightsaber prodigy and frighteningly powerful Force User, is similarly one of the best demonstrations of overall lightsaber ability we've ever seen. Dooku hasn't ever shown comparable ability with a lightsaber.
Dooku has also never used the Force to dominate someone like Nomi Sunrider, and Ulic dominated both her and his brother Cay simultaneously.