The Concordant Knights are a defunct order of angelic peacekeepers. According to Payapop Pritrum in the 5th Treatise on Aeons, the order was established with the purpose of protecting reality. It is implied most, if not all angels were allied with the Concordant Knights, but when the Universal War broke out, the order was functionally dissolved.
82 White Chain Born in Emptiness Returns to Subdue Evil still considers themselves to be a Concordant Knight.
The Concordant Knights were founded some time before the Universal War, likely during the angelic reestablishment in Throne. For many years they maintained peace throughout the multiverse, handing down martial arts dating back thousands of years and teaching the ways of law enforcement. Through the process of reincarnation, it appeared the angels would always remain loyal to the order.
However the Concordant Knights were unable to survive the Universal War and became splintered by violent upheaval. The Shattering killed an inestimable number of warrior monks, leaving a generation of young angels without leadership. Upon witnessing this destruction, most of the survivors became disillusioned with their ability to enforce the law. Some became independent and chose to sell their services as mercenaries, while others gathered to form the order of Thorn Knights. Those who remained continued their peacekeeping duties by establishing the Concordant Harmonies.
He who drinks oceans of blood shall never cease bleeding from the mouth.