The freezing temperature successfully affected Sebastian, as Kai planned.
Sebastian's speed slowed down, and even his thinking became slower due to the temperature invading his body from his amputated hand.
Kai arrived before him and stabbed him with his sword. He applied every basic principle of swords to that stab.
Sebastian blocked promptly, he stumbled and fell backward. Kai didn't give him any chance; he used every single basic move to perfection while also adding principles of other moves to it.
Kai hadn't fought with the sword like this for a long time. He never got a chance to perform his basic techniques since most of his opponents were too strong or too weak.
Kai slowly gained an advantage in the clash, and Sebastian became more passive. Due to not having an arm and the interference of an icy environment, Sebastian wasn't able to show his skills perfectly.