Holders of the 12 Heavens Blades, they cream of the Military Artists in Grendan. Compared to regular Military Artists their skills and powers with the Kei are monstrous. Each of them could be considered an army on its own.
Heavens Blade Successors are Military Artists with almost monstrous amount of skill and power. They were born with incredible talent in fighting and at controlling Kei. Their abilities are many notches above that of a regular Military Artists. It's nearly impossible to match a Heavens Blade in anything related to fighting. Be it speed, strength or the execution of their techniques; they are all flawless. Unlike regular Military Artists, Heavens Blade Successors are fighting almost exclusively alone. Their power allows them to defeat entire armies of Filth Monsters with little problems.
It's worth nothing that the Queen of Grendan, Alsheyra Almonise is even stronger than a Heavens Blade. So much she can effortlessly beat them in a single battle. Compared to Heavens Blade Successors, the gap of power is so huge as the gap between a normal Military Artist and a Heavens Blade Successor.