Ok, so all we know about the Warden Eternal is that he's a Forerunner A.I construct, he uses constraint fields like the Ur-Didact did, he's able to do a high-speed dash attack to catch enemies off guard, it's a "Keeper of The Domain and her secrets", and it wields a double-edged hard light longsword. But, there are still so many questions. Was he a Warrior-Servant of the Promethean rate that got composed? Is it a singular entity or one of many so-called wardens? Again, so many questions, but so little answers.