21 level scale

Robert Jordan initially said that he knows the relative strength of every female channeller in the books imposed on a 21 level scale.
I have said that in my notes I have such a scale that I use to keep track of everyone, but its main use is for the lesser characters, in particular Aes Sedai, so that I can check on who should defer to whom, who should only listen a little more attentively to whom, and so forth.Robert Jordan on his blog
This was later expanded twice. The first was a new scale of levels between 1 and 60. Later again he added 12 levels above the former 60 levels scale. In his notes Jordan explained that on the 60 level scale the Aes Sedai were comprised between level 1 (the level of Elaida, Romanda Lelaine, Moiraine, Siuan, the strongest living Aes Sedai at that moment, because Cadsuane was believed dead) and 33 (that of Daigian, the weakest living Aes Sedai); between 33 and 60 were comprised the female channellers too weak to be tested for the shawl. The arriving in the Tower of Nynaeve, Elayne, Egwene, and the return of Cadsuane needed a scale to classify better the stronger channellers above the level 1. So the 60 levels became 72, and the former level 1 became the level 13(1). The new first level, the level of Lanfear, was indicate as 1(+12). For instance that of Cyndane 2(+11), Nynaeve 3(+10), Moghedien 4(+9), Elayne 8(+5), Nicola 9(+4), Meilyn 11(+2). This is the classification that we can find in the "The Wheel of Time Companion" and is to be taken as canon, barring one or two errors.
Prior to this, efforts were made to construct the 21-level scale based solely on (sometimes unrelaiable) quotations from the books. What follows is a summarised table from the 13th Depositoty Blog.13th Depository Article
Rank 	Aes Sedai, Accepted, Novices 	Forsaken 	Wise Ones 	Windfinders 	Kinswomen 	Damane
1The strongest, maximum level known since the Breaking 	- 	Lanfear 	- 	- 	- 	Alivia
"Alivia is...considerably stronger than Nynaeve" (maximum)
2After her reincarnation in Cyndane, Lanfear was a little weaker than before, but still stronger than Graendal 	- 	Cyndane"The girl was stronger in the One Power than she herself! Even in her own age that had been uncommon among men and very rare indeed among women" Graendal on Cyndane (TPoD Ch. 12)	- 	- 	- 	Alivia (min.)
3Graendal is second in the One Power only to Lanfear and few were able to match her 	Sharina 	Graendal 	- 	- 	- 	-
4Nynaeve is defined the strongest Aes Sedai since the founding of the Tower 	Nynaeve 	Semirhage 	SomerynShe credits herself with never having met a woman who is stronger. That was, until she met Graendal 	Talaan"Talaan matched her as closely as made no difference...the light alone knew what her potential was"- Nynaeve's PoV (WH, Ch. 10)	- 	-
5Minimum level for female Forsaken 	- 	Mesaana (min.), Moghedien 	Tamela, Viendre 	- 	- 	-
6Ranked among the strongest Aes Sedai since Cadsuane, just a level below the Forsaken 	Egwene, Elayne 	- 	Aviendha 	Metarra 	- 	-
7Cadsuane was the strongest Aes Sedai in a Millennium until the arrive of Nynaeve, Egwene and Elayne 	Cadsuane, Bode, NicolaBode and Nicola have a potential strength described as not far to that of Egwene 	- 	Therava 	- 	- 	-
8Aes Sedai on this level, or more, are considered very strong 	Kerene, Meilyn, Nissa 	- 	- 	- 	- 	-
9Minimum to use the Choedan Kal safely. In the last twenty years Aes Sedai on this level were on the top of the White Tower hierarchy 	Elaida, Elle, Jancy, Lelaine, Moiraine (old), Romanda, Siuan (old) 	- 	Amys (max.) 	Rainyn 	Garenia/Zarya 	Sera
10The sisters on this level are considered very influential Aes Sedai 	Aisha, Cetalia, Katerine, Larelle, Leane (old), Ludice, Merean, Merise, Pevara, Saerin, Sheriam, Theodrin, Valera, Yukiri 	- 	Amys (min.), Edarra, Mora 	- 	Kirstian, Reanne 	Charral
11Aes Sedai on this level (or more) are defined strong; minimum to become Amyrlin Seat, that usually are chosen among the strongest Aes Sedai 	Anaiya, Bera, Beonin, Berisha, Carlinya, Coiren, Desandre, Faolain, Felaana, Galina, Joline, Kiruna, Kwamesa, Lemai, Maigan, Marith, Morvrin, Myrelle, Nesune, Nisao, Sierin, Silviana, Talene, Tamra, Tarna, Teslyn 	- 	Leyn, Melaine, Surandha 	Caire, Tebreille 	- 	Dali, Dani
12Minimum to be an influential Aes Sedai; minimum also to become Sitter, Ajah Head, Keeper of the Chronicles, Mistress of Novices 	Adelorna, Aledrin, Alviarin, Amira, Andaya, Anlee, Barasine, Berana, Danelle, Delana, Doesine, Duhara, Eadyth, Erian, Escaralde, Evanellein, Faiselle, Farnah, Faeldrin, Ferane, Gabrelle, Gitara, Juilaine, Javindhra, Janya, Jesse, Liandrin, Lirene, Lyrelle, Magla, Malind, Masuri, Moria, Naorisa, Raechin, Rafela, Rina, Rosil, Rubinde, Salita, Samalin, Sarene, Saroiya, Sashalle, Seaine, Sedore, Serancha, Shemerin, Shevan, Suana, Takima, Tiana, Toveine, Tsutama, Varilin, Velina, Viria	- 	Alarys, Belinde, Dorailla, Meira, Modarra, Rhiale, Tion (minimum for all of themthey were "Chosen from the strongest of the Shaido Wise Ones who could wield the One Power" along Therava and Someryn)	Shalon 	Sumeko 	Lidya
13Quite Strong Aes Sedai. Minimum for opening alone a suitable gateway to travel 	Alanna, Annoura (min.), Covarla, Eldrith, Falion, Ispan, Meidani (min.), Merana, Narenwin, Nesita (min.), Nimri (min.), Seonid, Serinia, Verin 	- 	- 	Chanelle, Dorile, Kurin, Renaile, Senine, Shielyn (min. for all of them) 	Julanya, Keraille, Sabeine, two between Kema, Nashia and Sarasia (minimum)Crossroads of Twilight Chapter 12	Mika (minimum)
14Just a level above average Aes Sedai 	Aeldene, Asne, Chesmal, Demira, Edesina, Elza, Lusonia, Marillin, Merilille 	- 	Tialin 	- 	- 	Mylen, Pura
15Medium level of strength, average Aes Sedai 	Adeleas, Akarrin, Kairen, Sareitha, Temaile, Therva, Turanna, Valinde, Vandene, Vasha (minimum), Zerah 	- 	Micara 	- 	- 	Guisin
16Not very strong, but linked in a circle of two elements they are able to open a small gateway, merely large enough to go trough 	Aiden, Berenicia, Cabriana, Careane, Kumira, Leane (new), Hattori (maximum), Jamilila, Nalasia, Nisain, Phaedrine, Shemari, Siuan (new), Teramina, Zemaille 	- 	- 	- 	Berowin 	-
17The weakest Aes Sedai. They were barely strong enough to gain the shawl 	Adine, Daigian, Elin, Reiko, Shana 	- 	Monaelle 	- 	Derys 	-
18Quite weak. Barely strong enough to become an Accepted 	- 	- 	Daviena, Losaine 	- 	Sarainya 	-
19Weak, even not enough to become Accepted; but some of them have a strong talent in Healing or in other weaves; Sorilea has the talent to learn a weave after seeing it only one time, like strongest channellers as Alivia	Moiraine (new) 	- 	Sorilea 	- 	Asra, Jesamyn 	-
20Very weak; but linked in a circle of four they are able to open a suitable gateway 	Setsuko 	- 	- 	- 	Alise, Caiden, Kumiko 	-
21Minimum known, barely able to touch the source and to form a weave 	Morgase 	- 	- 	- 	- 	-