Brianna wearing her mother's robe This particular robe originally was owned by the Jedi Master known as Arren Kae. It was later given to her daughter, Brianna, sometime following Arren's demise at Malachor V during the conflict known as the Mandalorian Wars. Brianna, who was one of the Lost Jedi and a companion of Meetra Surik, was previously referred to as the "Last Handmaiden" when she served the Jedi Master Atris. This is the reason for the robe's designation.
Within the game's narrative, Brianna will only join the Exile as a companion if the Exile's character is male. After their initial sparring match, the Exile, while already clothed, needs to instruct Brianna to get dressed. At that point, she will put on this very robe. Brianna is uniquely the only character who has the ability to equip this specific item.