Joe's special trait , the thing that made him superhuman , was super healing.
He was the first to realize it, and he realized it quickly. The others figured it out soon after, but Joe understood it immediately because of everything he'd put his body through during training.
Back when he fought Aron , the moment when he finally unlocked the power of the Vow , Joe had been in a terrible state. Out of everyone, he had been the most injured. Aron's attacks weren't random or shallow. They were meant to terrify Joe, to make him break from the inside out.
Aron had stabbed him several times. The wounds had cut deep, deeper than they should have for someone still able to move afterward.
Normally, wounds like that would take far longer than a week to heal. Even with medical attention, with rest, with luck… his body shouldn't have recovered that fast. But Joe's wounds had healed within days , inside the time frame where scars should have still been raw.
