The aura the unconscious Cassarae was giving off was making Sylas' skin prickle, his hair standing on end. He knew that getting close to her now would be a problem, but he also didn't just want to not do anything.
Sylas had gone through several Class advancements on his own, so he wasn't exactly sure why this one was so exaggerated. He certainly couldn't remember ever losing consciousness because of one—at least not when it was directly related to the Class itself.
Usually, if he was losing consciousness during an upgrade, it would be because he was heavily injured beforehand.
To be fair, he hadn't really had the time to assess Cassarae's injuries when he appeared. If she really had cleared the Gold Leg of her Quest, then it also meant that she had been embroiled in battle for quite a while.
But on the other hand… Sylas' instinct was that this state of unconsciousness had nothing to do with her injuries at all, he was sure of it.