Before deference becomes more than a smile and nod ... Felaana is a 17 and she didn't have much deference for Katerine on level 15 or for Merean and Lyrelle on level 14.

It's only situations like Merana lacking self confidence when the embassy collapsed that put her in an awkward spot with two much more forceful women, Seonid had little issue standing up for herself and she's a 17 too. We see clear deference when we get to women like Siuan being faced with Lelaine. And Delana intimates that she should have deferred to Siuan, but wasn't made to because of Siuan's personality.

Strength and position do have a pretty strong correlation as you'll see that the strongest women all hold important roles (or have to work to stay out of them as Moiraine did), but as you get to the lower levels it's very few who have official position. Below about level 21 it starts to become rare that a woman becomes Sitter or Ajah Head unless she's particularly forceful in her personality. Magla is the lowest level Sitter that I could find at level 29 and some of the "too young" Sitters are level 25-27, but that feels a bit deliberate to me ... almost as though the Ajah Heads hand picked women who could be easily controlled through deference as well as age. But that's just a random observation.

Also interesting to note is that all of the Ferrets were at least a level 19, which makes sense given that they would want women who would have an easier time being listened too in the Tower.