A Different Kind of Zombie

[Pursuivant]

The controlling necromancer will have Mindlink with their zombies.

The slow emergence of the zombie's original personality seems like a limitation to Slave Mentality. As the personality begins to emerge they might develop traits like Compulsive Behavior, Confused, Indecisive, Low Empathy, Oblivious, and Phobias.

A modified form of Racial Memory might represent their memories of their previous existence.

Many of the physical traits the zombies develop as their memories return represent removing disadvantages.

The "Immediately becomes a rotting corpse when slain" bit is a Perk - attackers might need to make Fright Checks and they're far less likely to loot the bodies.