At the time we met Tamela and Viendre neither Aviendha nor Elayne had reached full potential and Elayne doesn't specify on Potential Strength or current Strength. Either way it doesn't make much difference as skill is what she is really referring to in this instance. As another poster commented Aviendha has had a lot more experience with other Channeling groups than any other Aiel so she has picked up many skills no Aiel woman possesses