She has long white hair to her waist. 
Eadyth was the First Selector of the Blue Ajah, as well as a Sitter in the Hall. She was considered one of the most capable Blue in the last one hundred years and was First Selector during this time. 
She is the one who has to explain, reluctantly, about how an Aes Sedai must always defer to someone who is stronger than her in the Power.  Eadyth also gives Moiraine and Siuan letters-of-rights for their annual stipends of a thousand gold crowns.
It can be rather safely assumed that Eadyth has died since the Aiel War, as she is not mentioned in the main series, and such a prominent Blue would surely have been on, for instance, the Salidar Six, had she for some reason stepped down from her position. Furthermore, Lelaine Akashi is now the First Selector, and various evidence suggests Anaiya was so before her. Being a Sitter means that she was also a senior sister. She may have died of old age; she may have gone into retirement; she may have been one of the sisters killed during "The Vileness". She may also have been the Blue Sitter who was killed during the White Tower schism.