"...(Nynaeve) will shine like a bonfire beside the candles of Elayne and Egwene." Even allowing for some hyperbole on Moiraine's part, this has been consistent through the series. After pitting her strength against Rand's Egwene realizes she is well short of him, despite her lead from forced training and in the midst of expressing how far below his strength she is (despite earlier in that episode placing herself well ahead of Moiraine) she comments that maybe Nynaeve might possibly come close. Clearly Egwene and Moiraine both consider Nynaeve (and by extension, similarly ranked individuals such as Rand and the Forsaken) to be in an entirely different class, let alone simply stronger.