From what I could see in the video, it doesn't seem very impressive?
Phase 1: What he shoots is water, right? Or is it energy? Because if it's the latter, the lightsaber can easily absorb/reflect it. That wave can be easily dodged or blocked with telekinesis/barrier.
Phase 2: Seems more physical. Lucky for Childe that he doesn't use electricity projectiles since they could be absorbed/reflected. And lucky that he uses electricity weapons, which can block lightsabers. But it seems there's nothing special in this phase.
I think phase 3 has the abyssal thing, right?
I think everything is very easy for Dooku to dodge with his own ability + the Force powers. Of course, I'm considering that outside of the game mechanics, Childe fights like a real being and doesn't spend half the time standing still, so, like, him mixing phases 1 and 2 at the same time.
Because of Childe's barrier, I think he could block force pushes and Force Lightning, but the 4x thing will make it harder for him. If he can't block in time or the barrier is broken, I think those things could incapacitate him quickly, and are very easy/quick for Dooku to do.
Dooku also has the possibility of just pulling Childe with the Force and cutting him, since it seems that before transforming he doesn't fly and has nothing to anchor himself to the ground.
I'm not good at saying if one character is more skilled than another, but I think Dooku's ability + Farsight + Force Sense + precognition/danger sense + Instinctive Action/Perception amp + Statistics Reduction does all the work to surpass him in combat?
Aside from accelerated development and martial arts, it doesn't seem like Childe has that standard combo of powers that help in combat (like Instinctive Action, information analysis, Analytical Prediction, etc.).