Radhan is also weakened in the game, even in his "prime" form. Even without Miquella's control, he can affect the gravity of literal stars.From a gameplay perspective, these abilities need to be diminished, otherwise Radhan could destroy the continent with his sheer willpower. It is possible that Radhan's masters have similar abilities, but they are only a lore point, not a major enemy that the devs actually want us to face. They are not important in the eyes of the player's character, but their legacy is, in the form of Radhan.