This GodBracer is the one Magnian forgot to pick up when he left Obsardium. Shirian took it and followed Magnian to Earth so he can give it to him and also find out what will Magnian do to restore the planet Obsardium to normal. This contains the white SeiGear and it is the vessel for the god Dai Byakko.
This pendant is used to summon Shinma (machine) troops for offense or defense of the user. All Obsardian Towers have one (Magnian has one but he rather use magic instead). Each Tower has troops with skills based on their affinity. In Shirian's case, troops with specialty on melee combat.