"This makes sense because arts are similar to spiritual artifacts, like imprints in your mind. Therefore, although the legacy has it since your soul itself transmigrated, the art itself is dormant. Whatever method you shall use, the important thing is to control this wrath."
Arthur grasped the concept but found it hard to implement. This might be the first time in his journey that he had to retrieve something he knows exists but cannot access. Unlike the Art of Creation, Submission was an ability rather than a transcript.
To put it simply, Arthur found it easier to manipulate people. This made him remember where the "Art of Creator – Submission" originated from. During his battle against the Sin of Pride, Cassius, the calamity mentioned that King Arthur was inspired by him to use the art.