Steyr

A fellow Peacemaker like Cz, who comes to retrieve Cin who she claims is Cz in compressed form. She proves this by using her powers to revert Cin/Suin into what looks like an adult version of Cin/Suin. Of the Peacemakers, Steyr despises humans the most, angered at the 5000 years of "humans killing humans" she has seen. However, she is unaware that the Peacemakers, including her, are Valkyrie Types - an upgraded version of a Dragoon, and that she was created by humans, but got brainwashed into working for the enemy. Steyr's name is also mentioned as Stella. In her normal humanoid form, Steyr looks like a beautiful human woman with long pale blonde hair. Unlike Cz, Steyr is a civilian type cosmos guardian.

Almost succeeds in killing Shannon in his full D-Knight form, but is destroyed when she's speared through the head by all three Gigas' light lances. (Source: Wikipedia)