Although Vaan could achieve more incredible speed in deep space, he also lost the potential to use greater power.
After all, there was little-to-no resistance to affect his speed in near-vacuum space. Thus, he would stay in motion after using the initial momentum to travel. This was not even accounting for the acceleration factors to bolster his speed.
On the other hand, because it was also a near-vacuum space, there were basically no natural forces to strengthen the power of universal laws.
In other words, Vaan could only purely rely on the power of his comprehended laws and personal strengths and nothing else.
Given the present situation, Vaan had no effective means to defeat the pure earth elemental worm. This was the difference in their ranks. Vaan was too weak to compensate for the absolute gap in their strengths.
'I don't need to defeat it. I just need to lose it,' Vaan thought.
