I think if Ventress is losing a duel she could take Aayla out with the Force (KO, injure), theoretically. She's powerful enough to do so, and nothing Aayla has done with the Force is anything really impressive, IIRC. Doing that could take the pressure off her in sabers and could lead to a victory. I don't know who'd win in a strict duel barring Force usage, though.
I think Ventress has Round 2 in the bag.