to make more room for women like Bode and Nicola between Cadsuane and Egwene as well as to account for her being about as strong as Amys (45) and Melaine (35), and Moghedien higher than you to make more room for women like Tamela and Viendre and to make sure there is an obvious gap from Egwene up to Moghedien ... in the end it doesn't make much of a difference though.

I make Moiraine just under 50% of maximum strength because I think AS in general skew toward the weaker side of Average. Cadsuane made mention in NS that 1000 years earlier there would have been 50 women of Moiraine's strength in the Tower and a good many Stronger, so I put her just under the 50% point to account for that statement.

I also admit that the dexterity bonus may get smaller as you go down the scale or could be different in every woman ... perhaps Moghedien gets a smaller Dexterity bonus than Graendal, thus making the effective gap between them even larger than their strength gap... or perhaps Siuan is more dexterous than Cadsuane makeing the effective gap more narrow than their actual strength gap ... we don't know enough of that particular measure to be certain.

One other thought occurs to me the Aviendha quote about Egwene's strength is probably more likely a look at her absolute potential not her current strength ... Aviendha is very new to Channeling at this point and probably doesn't know the difference yet. Egwene could likely have been about a 65 to Amys 45 and the shield would have held, but been a challenge for Amys to hold for a prolonged amount of time. By the time Egwene gets to Salidar Elayne is likely around a 60 and Egwene a 70 or so with Nynaeve probably up to the low 90s.