Cognus loses a direct fight, and while I'm a little rusty regarding her feats wasn't she using stealth and different tactics to evade Set Harth? If she can go from room to room, and use stealth the environment seems better suited than an open area where Sing can perch and snipe. She also dodged Banes lightning and was faster than Set Harth (Harth could dodge blaster bolts). So she'd probably opt for a hit and run
Leaning Cognus
__________________ "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
Kind of difficult to say. Her suppression abilities may only hinder Aurra. But at the moment I don't quite remember if that's all it does or Harth and Bane were actively resisting it.
That said Aurra is a master of all weapons. Vibroblades, blasters, and several other techniques. Even without her Force connection Cognus would be hard pressed in trying to combat Aurra Sing.
I'd say Aurra wins. Although it all depends on Cognus' suppression ability.
K. I was thinking of before the fight but thats prep so whtevr.
Another factor is that Cognus only needs to nick Aurra since her blade is seriously poisoned. I think she can do it. She's also got flash grenades and maybe some other things.