Berylla is lean, almost to scrawniness. She has black hair and dark brown eyes.
Berylla is not particularly strong in the One Power, she was one the weakest in Liandrin's group. Her level of strength is described by "The Wheel of Time Companion" as 27(15) which is a middle level in Aes Sedai hierarchy. With this level of strength she is unable to open alone a suitable gateway to Travel.
She is as fine a manipulator and plotter as there ever was.
She was part of the group led by Liandrin that left the White Tower and made for Tear. When the Stone of Tear fell to the Aiel, the group fled to Tanchico. After their plans were foiled by Elayne Trakand and Nynaeve al'Meara, they were forced to leave.
Her fate is undisclosed.