Zayne had passed the first stage and that was already an accomplishment, but there were two more to go, and that alarmed him. He had enough willpower to make it to the very end, however, his body had a limit that he couldn't control.
If his wounds caused him to lack the strength to even stand on his own two feet, it would be over for him at that moment. Willpower influenced his mind, but it couldn't magically give him energy.
But, Zayne wasn't the only one who realized this. In the beginning, Chaos Trial gave Zayne a choice, and he decided to take the amulet with three signs, so... there was a reward for choosing the harder option.
Zayne didn't know this, so he didn't realize that the fruit in front of him wasn't something bad or part of the second stage. It was his well-deserved reward and a short break before moving on.