Jezrail is a dark, square-faced Tairen.
Jezrail does not show too much deference to Katerine Alruddin, so she can't be too weak. Because Katerine's level of strength is 15(3), it can be guessed that Jezrail level could be between 19(7) and 15(3) in the top ten levels of the recent Aes Sedai hierarchy and enough to open alone suitable gateways for Traveling.
Jezrail almost married a young man before she came to the White Tower. She still keeps a miniature of him and speaks fondly of him, even though his grandchildren would be grandparents now. That would probably make her over one hundred years old, likely even older.
She prevents Katerine from using the One Power to punish Egwene al'Vere when she makes a display in a novice class by splitting her weaves fourteen ways, a deed that impressed Jezrail. She grabs Katerine's wrist and admonishes her for going too far, as Egwene was in danger of being injured. Jezrail also seems to dislike anything related with forkroot.
Jezrail is one of the Red sisters, along with Pevara Tazanovni, Javindhra Doraille, Desala Nevanche, Melare, and Tarna Feir, sent to the Black Tower to put the proposition of Red sisters bonding Asha'man as Warders to Mazrim Taim. He has agreed to this.