If Rand could wipe the floor with her, he would never have thought that playing mind games with her is dangerous.

She is obviously a major physical threat. She threatened Lanfear. She threatened Rand. She showed considerable rationality when weighing Demandred against Semirhage, but felt fear at facing neither.

Where others are thinking of killing Moridin, she actually contemplates enslaving him, and if the various comments of Rand, Sammael and Demandred are anything to go by, she's capable of it.

I think that the differences in strength between the Forsaken are so thin that the weakest can challenge the strongest, and the battle can go either way. Which is why Demandred doesn't want to face Rand till he has a sa'angreal. No one at these levels has an unassailable lead unaided.