This gentleman created a video that covers the prototype. Its designer, lineage, loadout, and everything else. Then recreates and plays it within Armored Core.
https://www.youtube.com/watch?v=vqsd5OXzacU
The prototype is from this Halo Legends short which has been timestamped for easy watching https://www.youtube.com/watch?v=q-JSCbHAaJ8&t=3973