Gravis continued to circle the earth shield with his superior speed. Acceleration took way more Energy than stopping or keeping the speed going, which was why he didn't stop. Yet, Gravis was still continually using up some Energy to keep the Law of Lightning Speed going.
He wasn't using it to its full effect, but he needed to use it to uphold his speed advantage. Additionally, he used the pulse to give his body a boost for every step.
Time passed, and fewer and fewer attacks came from the Inquisitor. The Inquisitor saw that Gravis was using a Law to keep his speed going, and he was sure that Gravis would run out of Energy first. After all, there was a difference of three levels between them.
