Skylar realized that he was falling down soon after. He was in the air and had no support. There was no way out. He was going to fall on his back.
But that didn't happen either because Arthur rotated his whole body along with his left leg. He turned in such a way that his right leg shot up as soon as his left leg gained support on the ground.
What he had performed was a roundhouse kick. His kick struck Skylar square in the same spot he had been touched in.
Arthur's right leg used the momentum of the rotation of his body and the support of his left leg to strike Skylar with far more force than his punch had delivered.
The impact of the kick was so powerful that Skylar flew through the air and struck the ground with enough force that he kicked up sand and bruised his back.
It would have been if he had just fallen on his back earlier. But Arthur wanted to make sure that falling down truly hurt.