Even though Yoze knew that vanity must have played a small role in Geo's decision to strengthen and modify his hair, he didn't feel that it was the major reason. He felt that the probability that his hair had some special function for his spells was much more likely.
Throughout most of the entire battle, Geo relied more on his martial art skills to fight him, but for someone who had spent more time developing his skills as an immortal cultivator, he should have much more powerful spells that didn't rely on his martial arts. However, what made Yoze certain that Geo was holding back was that he didn't look like he was running out of crystal energy.
To still be able to keep his reserves of crystal energy high while fighting a strong opponent could only mean that Geo was holding back because of something. If Yoze had to guess, he felt that Geo was holding back because of the ten Shadow Lords who were still casually watching their battle.
