The full name was not recorded in the main series, but was given in the Wheel of Time Companion. Other information about the character is also included in the Companion, but we did not use it in the TarValon.Net Library.
Author: Atarah al'Norahn
Sybaine is one of the thirteen Counsels of Far Madding, the group that rules the city.
She has hair as gray as Cadsuane's and slim hands.
When Cadsuane, Rand, Nynaeve and company are in Far Madding, Sybaine and the other twelve Counsels meet with them. When Cadsuane is trying to negotiate Rand's release, she tells the Counsels that the three men with her (Damer, Jahar and Eben) are Asha'man. Sybaine sags back in her chair and begins to fan herself.
(Reference: Winter's Heart, Chapter 34)