A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard's downfall, he used the wizard's body as a springboard to gain influence and power in his new world.
People usually would develop a habit of giving orders when they were in high positions long enough. Even if it was not very obvious. There were always traces to show. Without close observation, Anfey could tell who was in lead.
Sometimes experience could help him make the right judgements, but those judgements could not be explained in words. If Anfey were asked to talk about the reasons why he believed that a particular person was in charge, he probably could not explain. He just knew it.
A legion like this one would pay attention to their surroundings to look for traces and be ready for their leader’s orders when they were on assignment. Maybe when they waited for their next order, it would sent out a message that Anfey could catch with his instinct.