Britomart was possibly a female knight or a warrior. She was strong, cunning, and a intimidating; according to Boy Blue. During her stay in the Last Castle arc, she was often seen with Robin Hood. Hinting they had formed friendship, to a point. In the beginning of the story, they placed a friendly bet of who could kill the most of the Adversary's soldiers. The loser would have to wear a dress. Much to his embarrassment, Britomart won and made him wear a girlish blue dress.
Her final action before being killed, was throwing her magical spear, which would find any target she set for it, killing the general leading the Adversary's forces. She and Robin Hood, both most likely died til their last breath fighting.