Yeah but to be fair I dnt think Dooku really wanted to kill Ventress. He tried to reason with Sidious about it, and when Ventress challenged him at the end by herself he warned her first "you're no match for me without you're monster."
On top of that Ventress probably just caught Dooku off guard with that deflect.
On the other hand when we see Yoda stop Ventress's lightsabers, that makes it pretty clear that he's light years beyond her in Force Power.
Ok so I think everyone is forgetting the fact that Darth Nox is not only incredibly strong with the Force but he/she also is insanely skilled with a double bladed lightsaber. Now I think that with that in mind in basic lightsaber combat that they would be fairly evenly matched. Though Darth Nox has the ability to use Force Shroud and come up behind Darth Tyranus. He probably could sense where Nox was but I believe that if he/she used Mind Trap, which probably wouldn't last too long but would still give a huge opening, he/she could hit Tyranus with a Thundering Blast and completely obliterate Tyranus. Though he/she wouldn't even need to go that far since he/she is so overwhelmingly strong with the Force. He/she could very easily hold him still and launch a blast of Force Lightning and incinerate him. It would be a fairly good fight but Darth Nox would easily win, hands down.
__________________ "Happiness is a lie. Life is horror. The light is always dying all across the universe. The last star will flicker out someday, when it does, all that remains is shadow. And I will be its king!"'-Amahl Farouk