[ revised by James Luckman]
The short answer is, she is a woman who used to be Aes Sedai.
"You were Aes Sedai, once,'' he said quietly, and her hand froze.
She recovered herself so quickly that he might have imagined it. She was stately Setalle Anan, the innkeeper from Ebou Dar with the big golden hoops in her ears and the marriage knife dangling hilt-down into her round cleavage, about as far from an Aes Sedai as could be. "The sisters think I'm lying about never having been to the Tower. They think I was a servant there as a young woman and listened where I shouldn't have."
"They haven't seen you looking at this." He bounced the foxhead once on his hand before tucking it
safely back under his shirt. She pretended not to care, and he pretended not to know she was pretending.
Her lips twitched into a brief, rueful smile, as if she knew what he was thinking. "The sisters would see it if they could let themselves," she said, as simply as if she were discussing the chances of rain, "but Aes Sedai expect that when . . . certain things . . . happen, the woman will go away decently and die soon after. I went away, but Jasfer found me half starved and sick on the streets of Ebou Dar and took me to his mother." She chuckled, just a woman telling how she met her husband. "He used to take in stray kittens, too. Now, you know some of my secrets, and I know some of yours. Shall we keep them to ourselves?"
[KoD; 9, A Short Path]
Is She the One Who is No Longer?
"The key to finding the bowl is to find the one who is no longer." [LOC: 19, Matters of Toh, 312]
Well, they found the bowl. "The one who is no longer" is still a mystery. So we should be saying, "the key to finding the one who is no longer is to find the bowl."
Aside from the clean logic of a woman who used to be Aes Sedai being someone 'who is no longer', there is the fact that if we look for one single person who was key to finding the Bowl of the Winds the most likely candidate is Setalle Anan, the innkeeper of The Wandering Woman. El and Ny's meeting with her set off the chain of events that led to finding the Bowl. (Anan introduced them to the Kin, who they got Mat to spy on, and when Mat followed one of them, she led him to the six-storied building where the Kin's stash of *angreal was.)
Was She Burned Out or Stilled?
Anan is most probably a burn out--her attitudes do not match that of a criminal; she is not furtive or secretive, displays no shame (and at times seems disdainful of the other Aes Sedai) none of which matches a woman who was severed due to a crime. Indeed whilst she would prefer the Aes Sedai not know who she was, she doesn't go largely out of the way to ensure that they do not. That seems more discomfort than shame at work.
In addition it is clear that the AS are not keeping tabs on Anan, and we know that AS tend to avoid Sisters who are severed accidentally. AS who are stilled for some crime, on the other hand, are often kept around the Tower to serve as examples.
A Kin Timeline
In [ACOS: 24, The Kin, 404]:
"Remember who she is, Garenia," Reanne said sharply. "If Setalle had betrayed us, we would be crawling to Tar Valon, begging forgiveness the whole way....She has kept the few secrets she knows from gratitude, and I doubt that has faded. She would have died in her first childbirth if the Kin had not helped her. What she knows comes from careless tongues...and the owners of those tongues were punished more than twenty years ago."
Which provides us with a lower limit. Setalle had been severed prior to twenty years ago.
Then we have the Garenia evidence: When Anan meets Garenia, she says: "Your name is Garenia? You look very much like someone I met once. Zarya Alkaese." [ACOS: 23, Next Door to a Weaver, 395]
Garenia puts her off by saying that Zarya Alkaese was her great-aunt, but we find out in [TPOD: 28, Crimsonthorn, 542] that Garenia is Zarya Alkaese herself, and ran away from the Tower seventy years ago. This provides us with an upper limit--Setalle was still at the Tower seventy years ago. So the timeline established is that Setalle was severed some time between twenty and seventy years ago.
Could she be Martine Janata?
Vandene mentions Martine to Elayne whilst warning her of the dangers of studying ter'angreal.
"She was the last sister to really make a business of studying ter'angreal... She did it for forty years, almost from the time she reached the shawl.... Then one day, Martine's maid found her unconscious on the floor of her sitting room. Burned out.... That was more than twenty-five years ago.... She vanished once she was well enough to slip out of the Tower." [TPOD: 2, Unweaving, 75-76]
The timing makes this possible, as explained by John Hamby:
1. The timing of her burning out leaves five years for her to wander, meet her husband and get pregnant in order to fit the kin's statements of when Setalle gave birth to her first child.
2. Martine Janata was raised to the shawl over sixty-five years ago, placing her in training at the same time as Zarya Alkaese.
Also it is a bit too pat that we get the story of one such sister that provides us with a chronology that fits the criteria to be Setalle Anan--burn outs are rare. Two such with such perfect timing seems unlikely.
Vandene makes clear Martine's fascination with ter'angreal--she studied them for forty years despire the dangers. In KoD we witness Setalle around ter'angreal.
"Joline must have tried to stop you. and Teslyn and Edesina as well, but whatever they did failed. I think that means you possess a ter'angreal that can disrupt flows of the Power. I've heard of such things-Cadsuane Melaidhrin supposedly had one, or so rumor said- but I've never seen the like. I would very much like to. I won't try to take it away from you, but I would appreciate seeing it."
[KoD; 7, A Cold Medallion]
"Could I see it? Just to see?"
There was no doubt what she meant. He hesitated, then fished in the neck of his shirt for the leather cord that held the medallion. He could not have said why. He had refused Joline and Edesina even a glimpse. It was a fine piece of work, a silver foxhead nearly as big as his palm. Only one eye showed, and enoughdaylight remained to see, if you looked close, that the pupil was half shaded to form the ancient symbol of Aes Sedai. Her hand trembled slightly as she traced a finger around that eye. She had said she only wanted to see it. but he allowed the touching. She breathed out a long sigh.
[KoD; 9, A Short Path]
Setalle shows a similar fascination to Mat's ter'angreal that one could see prompting a woman to study something so dangerous for upwards of forty years.
From the simple description of Setalle as one who is no longer Aes Sedai, combined with the role she played in finding the bowl, it seems certain that Setalle is the fulfilment of the Wise One's dream. From there the timelines in play combined with the similar fascination displayed by both woman towards ter'angreal make it very likely that Setalle is also Martine Janata.