She had pale skin with long black hair and was plump and curvaceous. She wore a kesiera, a thin silver chain with a moonstone dangling from it, in her hair.
Daigian is described as one of the weakest Aes Sedai ever. Barely being allowed to gain the shawl. This is confirmed in "The Wheel of Time Companion":
"...with a strength level of 45(33), the lowest level at which a woman traditionally was accepted for the Tower to become Aes Sedai"
Being the weakest Aes Sedai means that she was still stronger in Saidar than many Kinswomen, Wise Ones, and Windfinders and to be a woman with the authority and influence of the White Tower to support her. Although she accepted her low rank as an Aes Sedai, she insisted on proper respect from non-Aes Sedai.
Cadsuane thinks that she has an excellent mind.
Born in 907 NE, she was the youngest daughter of a lesser Cairhienin House, she went to the Tower in 921 NE. After spending twenty-seven years as novice and twenty-one years as Accepted (spending a longer time as novice and Accepted than anyone in living memory), she was raised to the shawl on 969 NE becoming the weakest living Aes Sedai.
Despite her lack of strength, she was much liked by many of her fellow Aes Sedai, and particularly of those not full recognized Aes Sedai, such as Nynaeve.
She was one of the Aes Sedai that accompanied Cadsuane Melaidhrin into Cairhien. She acted as Cadsuane's messenger to Rand al'Thor when he requested a meeting with her, giving him Cadsuane's answer of no. She Traveled with Cadsuane to Far Madding to track down Rand. She bonded Eben Hopwil as her Warder. Linked to him, she participated in the Battle near Shadar Logoth with Nesune Bihara and Beldeine Nyram. During the battle they fought Aran'gar. Eben detected her holding saidin and threw himself at Aran'gar, ultimately sacrificing himself.
She accompanied Rand and Cadsuane to Algarin Pendaloan's house in Tear, where Rand recovered after cleansing saidin. She wept in private over the loss of Eben. While in Arad Doman, she helped teach Nynaeve al'Meara the one hundred weaves required to become an Aes Sedai. She helped maintain Semirhage's shield while Semirhage was being interrogated by Cadsuane and Sarene Nemdahl. Nynaeve wanted to try to Heal her sorrow, convinced it had to do with the Warder bond being broken, and therefore with the Power. Daigian refused, preferring to cherish his memory with her grief.
She was killed during Semirhage's escape, most likely by Shaidar Haran, probably because she had no Warder who would feel what was happening through the bond. She was mourned particularly by Cadsuane and Nynaeve.