Centurions are the core of the field command of the Imperial army.
Their excellent tactical training and unparalleled field experience are crucial to the success of operations performed by empire forces.
In spite of this, Centurions are a subordinate entity only to the authorities of the Order, and their service to the forces of the empire is regulated by a concordat which is the basis for relations between the Order and the Empire.
They have access to some secret knowledge, but their understanding of magical practices is limited to simple chants useful in the heat of battle. Their fighting abilities and the influence they have on the morale of the soldiers surrounding them are definitely more impressive.