In order to prove her point of being able to defeat Author, she used her special talent and sped up to create some distance between herself and Arthur.
Arthur snorted and also sped up to catch up with her. He hadn't been flying at his top speed, so it was easy for him to catch up to her.
Her talent for improving the power of lightning had evolved when she reached the third mortal coil and fourth mortal coil. It proved to go from a 20% boost to a 50% boost and then to a 100% boost in power.
When this talent is combined with the amplification of the armament, it means that she can improve her power to three times its normal level. But Arthur was still able to catch up to her easily.
He could even surpass her, but he didn't just to edge her on. He caught up to her and asked confidently, "What else have you got?"
His confidence lay in the fact that he can enhance his power by five times due to the boost of the Mountain Karma divine ability.
