She is a pretty, hazel-eyed Arafellin, who wears bells in her dark, braided hair.
Samitsu's strength in saidar is at level 20(8) by the description given in "The Wheel of Time Companion". This strength is just enough to open a suitable gateway to Travel.
According to Cadsuane, she is the best Healer among living Aes Sedai and the best that the Tower has seen in centuries, perhaps ever. She has the ability to modulate the strength of the Healing weave (which very few people can do) and has the same ability with Healing as a full circle. The only other people in the series with Healing ability equalling or surpassing hers are Suana Dragand, Nynaeve al'Meara, Semirhage, the Asha'man Damer Flinn and Sumeko Karistovan of the Kin.
She manages to stabilize Rand al'Thor after he is stabbed by Padan Fain with the Shadar Logoth dagger. Subsequently, after witnessing Damer Flinn's healing on Rand's wound, she offered him gold, and even to bear his child in exchange for an explanation on how his Healing was accomplished.
She is left in charge by Cadsuane in Cairhien after she leaves for Far Madding. Unfortunately Sashalle Anderly doesn't submit to her authority due to her standing higher in the One Power and has begun to take command. She is called to Heal Dobraine Taborwin after he is nearly killed by robbers going through his room. Her confidence in healing was somewhat shaken after witnessing Damer Flinn's healing.
Samitsu then Travels to Tear to find Rand and Cadsuane and report all news that has occurred in Cairhien. Cadsuane sends her back to Cairhien, to keep an eye out for every activity Sashalle and the other Sisters there carry out.
Samitsu and Sashalle greet Elayne Trakand when she arrives in Cairhien and they pass all duties of rulership onto the new queen.
It can be safely assumed that Samitsu, like the other Aes Sedai in Cairhien, participated in the Last Battle. During the fight as a Yellow she probably stayed at Mayene to provide healing to the injured. It is presumed that she survived the conflict.