the orignal design was drawn up by Enclave scientists on the Oil Rig and under the direction of Autum Senior it went into its rudimentary prototype stages. Several were made and tested on the oil rig but the Athena Power Armor was never taken seriously. The destruction of the oil rig along with both protoypes and the development team meant that the power armor was for a time forgotten until Autum Senior drew up entirely new plans improving upon the old design and continuing work. But with his order to move east Autum sent his design east via a satellite signal several bases also recieved this including Raven Rock, the Chicago bunker and Mobile Naval Base in Alabama. Only in Chicago did the armor continue development under Major Nathaniel Baird and was eventually deployed. In Raven Rock it was used as a basis for the design of Hellfire Armor hence how similair the two look.
Only in Chicago was it deployed by the Enclave and was used to great effect against the Midwest Brotherhood chapter and the NCR in a brief Skirmish in and around Helios One. The Units using the Athena Power Armor are considered "Heavy Units" with every man in these elite battalions using the Armor. This armor is also used by the Enclave's Spartan Commando teams.