Given the Bell Curve we know exists, Moiraine needs to be closer to the 50 mark with standard AS falling closer to the 20-30 range. We know from Cadsuane that Moiraine is strong enough to be considered somewhat rare, but that there should be dozens more like her if the Tower was more willing to find them. Moiraine is likely right around the middle of the Bell with Cadsuane being far enough into the "rare" category that other AS have not randomly encountered other women in her strength range. Minimum for Cadsuane is likely around 60, probably higher given the quotes about sharp drops and the several women between her and Moiraine, she could be as high as 65-70, but there is really no way to tell for certain, all we know for sure is that she is quiete a bit stronger than Moiraine, and weaker than Egwene by some unknown margin.

Cadsuane also sheds light on AS mentality in general which likely explains why even the stronger women seem weak. She thinks it's surprising that so few AS innovate with the Power. Rather they learn the standard weaves taught at the Tower and accept that this is the way things work. IMO if more AS worked out alternative weaves to perform certain feats (i.e. worked to their strengths) they would likely seem more Powerful. We've even seen an example of this with Romanda who admits that she does not have the aptitude with the new Healing Weaves as she did with the original, but that there were many "older novices" who showed great promise with the new weaves, yet Romanda seems to have no interest in attempting to work out additional weaves that may play up her abilities and thus will eventually seem less effective. AS rely on raw strength which won't always allow them to accomplish a task. Perhaps Aviendha's Travel Weave would allow more AS to create larger gateways, or Cadsuanes differing fireball weaves would give more As significant ability there.

IMO at least part of why the FS appear so much more Powerful is that they were trained to thier specific strengths and then they each clearly innovated based on their personal strengths. Just knowing how to use the ability to its maximum effect gives the FS a huge edge ... And remember that they generally consider training and skills more than strength went they are sizing other channelers up. As Graendal said to Sammael, she would not risk Strength and Skill in the same place.

One last minor point is that Moghedien has met with other FS off screen even prior to being mind trapped. Graendal and she had semi-regular meets, Graendal tells Sammael that she suspected Moghedien was dead because she missed their planned meeting. Yes she is clearly the weakest of the FS, but she is also clearly strong enough and skilled enough to be in their ranks and senior enough amongst the larger pool in the AoL that she was attending top tier FS planning meetings and was one of the handful the DO allowed to use the True Power... And he only accepts the most Powerful by his own admission. Personally I think she has been her own worst enemy... Her cowardice seems to be the main reason she hides in the shadows and developed her kill from behind strategies. She could easily be as high as a 90 and would still be laughed off by the others because they know she is too chicken to confront them ... Much like Aginor, clearly of vast strength, but too meek to face off with those close in Power or even slightly weaker.