First off, we need to realize that there is no contest at all if Nynaeve has her angreal and ter'angreal. She isn't as unskilled as Alivia, and I doubt if anyone would stand a chance against Nynaeve at that point.

But, assuming Nynaeve and Egwene are going to fight without any additions, the situation isn't simple.

Without any doubt, Nynaeve is a clumsy weaver. Not because she's inherently unskilled but because she never practices and has shown no dedication to improve her skill.

Egwene, on the other hand, is shown to be a master at anything the Aes Sedai can weave, and there are no indications that the secret weaves she got from Moggy give her any trouble at all.

As RJ's statement showed, Egwene would breeze through the Aes Sedai test while Nynaeve, despite greater strength, would not. The test checks for one thing... weaving under pressure, and also using channeling to tackle other obstacles and distractions.

It is clear that Nynaeve will have to rely entirely on her strength for this, and that is going to be tiring. Someone like Egwene or Elayne, with their greater practice and broader knowledge, will not have this problem.

Over and above that, Egwene remains the only person who could make 14 weaves at once. Sure, Rand or someone might match that, but we haven't seen it. Rand says he can make up to 12 weaves at one go, and that is all we have evidence for.

Egwene can make fourteen when under the influence of Forkroot. That says a lot, because the ability to multitask is probably going to be crucial in any battle.

While not the strongest, Egwene has certainly shown to be the most dexterous channeler we've seen.

Therefore, I think she can take Nynaeve on, an in Nynaeve's current unpracticed state, Egwene may have the edge.