Many years ago, when Faceless was creating the modified version of the Faceless Art, he added a complex array that prevented all bearers of the Faceless Agent Mark from suppressing him, regardless of their strength.
Later, he made it so he could easily take away the power of the Faceless Agent Mark and even waive all restrictions on anyone who has the mark.
It wasn't because he didn't trust his assassins; he only put that condition in there to ensure moments when any of his assassins were to become puppets under anyone's control, they wouldn't be able to hurt him or anyone.
The Faceless Agent Mark isn't as simple as one might think. It actually brought out the Midnight Shadows' hidden potential.
Initially, the Midnight Shadows weren't a powerful assassin organisation in the universe. However, after the Faceless Agents started appearing, their power skyrocketed.
So he made sure they were protected, and that was achieved through the Faceless Agent Mark.
