Don't you think its weird to want to most competent to be the most strongest? Anaiya, I think, says that strength of will goes with strength in the Power, which is a bonkers statement.
Why shouldn't Mesaana be stronger in the Power but less capable and devious than Graendal?
The Forsaken almost never think about differences in their OP strength. That's because at their range, no one has enough of an advantage to think a fight a foregone conclusion. Instead they consider the deviousness, the plotting ability, etc.
It seems to me very current age Aes Sedai like to say "Mesaana should have been weaker IMO ... Level 2 just doesn't match up all that well to the books to me." You can be strong and inept! On the other hand, you can be as weak as Sorilea, or weaker, and be amazingly competent.
I know you're not saying otherwise. You're wishing otherwise. But that just seems weird to me.
More later.
I'm not really "wishing" for anything here, I'm noting where I find discrepancy in how I read the text and what the Companion says regarding strength. RJ set the stage in many ways to show that stronger channelers were typically more bold, you can see that just by looking at the strength rankings and looking at how these individuals behaved.
I found it odd from Mesaana's behavior that she was so strong in the power. She behaved as though she was less than the other Forsaken, even while talking about how she knew she "matched up in skill" she was admitting being afraid of Semirhage. I don't actually think Mesaana was particularly inept, she showed quite a bit of skill actually and created more chaos than any Forsaken save Graendal really. But the hiding, fearfulness and generally meek attitude went a long way toward assuming she wasn't as powerful in the OP.
I think what Anaiya's comment is supposed to mean is that being strong gives you a bit of swagger, that doesn't seem crazy to me, especially from a modern Aes Sedai. But I agree that we've got plenty of examples of strong people being inept as well as weak one's being effective ... look at Shemerin, she was a level 15, quite high for Aes Sedai, but was also totally inept! Something RJ had to go out of his way to explain (she's got one of the more flushed out entries in the Companion)
It's exception when someone weaker is exceptional, that's pretty consistent throughout the books, so much so that RJ went out of his way to point it out most of the time. Cadsuane had to tell us that Daigian had "one of the finest minds" in the Tower, yet she still spend 48 years in training (close to 2x the next slowest learner). All part of his illustration of her power level. Mesaana had weak motivations for turning to the Shadow, did comparatively less than others during the WoP and generally hid behind an alliance with more powerful allies. Adds up to a weaker individual IMO.
But you are correct that there is so little real difference in their individual strengths that it offers basically no advantage to any of them. Even Moghedien, had she been less inept, could have been a threat to the most powerful in terms of power levels.