Valencia was an inhabitant of Camelot and sister to Ramus. She helped SG-1 find Merlin's library on her home planet. In the fight with Merlin's Black Knight she successfully pulled out the Sword In The Stone, helping Lt. Colonel Cameron Mitchell to fight the Knight. It bought Mitchell enough time to fight it, and eventually it was enough time for Dr. Daniel Jackson to destroy the crystals controlling the Knight.
Atypically for her time and place, Valencia wanted, despite being a woman, to actively defend her home and fight for her people, an unsuitable ambition in the eyes of many around her. (SG1: "Camelot")