A similar entry appears in the Wheel of Time Companion confirming the information available in the main story arc.
Panarch is the title for the female co-ruler of Tarabon. The Panarch has her own palace (TSR, Ch. 11) and guard (TSR, Ch. 11). She and the King are elected by the assembly (TSR, Ch. 38). When Tarabon was founded, the founders, Boral Amadia, Tazenia Nerenhald and Haren Maseed instituted a system of government based on that of Balasun, where a king or queen would be balanced by a Panarch of the opposite gender (The Wheel of Time Roleplaying Game). By around 500NE, the primary ruler was always a male and the Panarch a female. the banner of the Panarch is the Golden Tree of Tarabon with a green staff behind the tree (The World of Robert Jordan's "The Wheel of Time", Chapter 30). The Panarch's personal Guard is the Panarch's Legion.
The Panarch of Tanchico is the equal of the king in authority, she is responsible for collecting taxes, customs and duties; he for spending them properly. She controls the Civil Watch and the courts, except for the High Court, which is the king’s. The army is his, of course, except for the Panarch’s Legion" (Elayne,The Shadow Rising, Chapter 11)