Reputation can be very convenient at time, but it can also cause a lot of trouble. Anfey wasn’t the most famous person, but he wasn’t unknown, either. If he had been more famous, maybe convincing the mercenaries to join him would have been much easier. He could move through the sea of death because he wasn’t famous enough for everyone to know.
The necromancers did not pay much attention to him. They were more worried about Suzanna. They did not know the mercenaries had a top level power until they saw the blinding combat power.
Whether he wanted to or not, Anfey knew this was his only chance of breaking through. Fernando could press ahead without any concerns, but the necromancers needed to spare part of their force to attack the mercenaries. The fight for the Book of Life was almost as important as the entire battle itself.