As part of him being a son of Athena, Hephaistion didn't like not to know things. He couldn't predict that a simple lunge from the wolf would re-injure his shoulder; he didn't anticipate how quick the wolf would be; and he didn't realize that this young girl was clearly a better match for the wolf than he was. The gods gave them each different powers, and Sky had the advantage in this fight. She was between him and the wolf now, so he held his ground as her backup, ready for if the wolf provided him an opening.