She has round cheeks.
During the use of the Bowl of the Winds Rainyn's strength is described to match Lelaine Akashi's strength, who is at level 13(1). So by Aes Sedai standard Rainyn can be considered strong in the One Power, also equalling women such as Romanda Cassin and Elaida do Avriny a'Roihan.
This level of strength is confirmed by "The Wheel of Time Companion" and it is more than enough to open by herself suitable gateways for Traveling.
She Travels with the the rest of the group led by Nynaeve al'Meara and Elayne Trakand from Ebou Dar to the Kin's farm with the Bowl of the Winds. She is part of the thirteen women who link up and channel into the Bowl of the Winds to change the weather.
They Travel to the area where the Black Ajah are riding a wagon with Elayne inside. The strike force ride towards the wagon, but are decimated by Balefire from Asne Zeramene. Birgitte finally convinces the Windfinders to actively attack the Black Ajah. The Windfinders all link with Chanelle in control and attack the wagon with lightning, killing Asne in the process. They shield all the remaining Black Ajah members so they can be taken captive by Elayne's troops.