She was a bony woman who looks very plain.
Larissa was not particularly strong in the One Power. Her level of strength is described by "The Wheel of Time Companion" as 28(16) 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 had sided with the Rebel Aes Sedai.
She missed Nynaeve al'Meara Healing both Leane Sharif and Siuan Sanche from stilling and insisted on her going through the whole process again step by step and even tried to give advice on how to improve it.
In Verin Mathwin's list of Darkfriends, Larissa is noted to be of the Black Ajah. It can be assumed she was one of the fifty Black sisters to be executed in the rebel camp.