From the post:
Although the Tactical Dreadnought Armour project was conceived first and foremost for the use of the Legiones Astartes, it was inevitable given the success of Terminator armour that its principles could also be adapted for Legio Custodes use. The first pattern developed was what became known as Aquilon armour. Advancing yet further upon the Cataphractii Terminator armour patterns, the Aquilon pattern takes into account the enhanced physique of the Legio Custodes as being able to bear more weight and strain than even a Space Marine, and so is fitted with additional integrated power systems and capacitors which make up for some of the limitations of the origin pattern. This allows for the Cataphractii Terminator armour’s famous durability to be retained in the Aquilon pattern, but with a degree of speed and manoeuvrability the former lacks.