Eao was an Ahamkara who (depending whether Bungie made this thinking about HoW only or future lore from TTK) either... A) (Most likely) who attempted to, in some way, stop the Great Hunt from succeeding, or is the last living Ahamkara, perhaps ascending above a mortal body, or lost a limb which created the artifact and boots, maybe even the Ahamkara that certain Hunter came out to find. B) Tried to stop the Worms from doing evil (possibly referenced in a Warlock artifact, Sins of Kharad-Tan [the Worm Yul being Kharad-Tan?]) and Eao being the first hero, and Yul the first villain.