I don't think you need SUPREME skill to be Egwene level and pose a threat to the Foresaken. You might need that level of skill to be able to guarantee your survival every single time, but not if you want to pose a reasonable threat.

I think you're shooting your own argument about the importance of strength in the foot by insisting you need enormous skill to overcome the strength gap between Egwene and the Foresaken. Demandred would be content with a mere angreal then, to challenge Rand. He wants a sa'angreal, though, even though he's just a little less skilled than Rand.