About the Doomslayer's armor.

[MTF Sergeant]

Wasn't the Praetor Suit retrofitted with UAC tech when they dug him up, with the HUD and ability to interface with human tech (Health Terminal and the such)? Besides, the specters of the Night Sentinels seem to recognize him or at least be sympathetic when they try and guide him through Argent D'Nur. While that doesn't prove he was one of them, it is a strong indicator, it seems. Also, there's a bunch of statues of someone wearing the Praetor Suit in the hell dimension, even a big ass one in the Well Cathedral.

[Nevander]

Sorry, what's the question?

[Aquila Chrysaetos]

I think the question was, "Was the Preator Suit retrofitted with UAC tech after they found the Doom Slayer or was it always like that?"

Okay.

[Robo_Cola]

I think one of the codex entries stated that the armor was impenetrable to their technology when they tried to pry it open, so I'd assume it was not retrofitted. 

[eharper256]

I always assumed that the Praetor suit was what Doomguy had customised from his original human armour over the years, so deep down in its foundation, it still has the ability to use UAC tech from a different dimension, even after the Argent d'nur modifications (And seeing Classic Levels appear in the modern ones is the old HUD playing up and throwing glitches). But then, as you can tell, I'm a fan of the theory that the Doomslayer and Classic Doomguy are one and the same guy, who was dimension hopping and demonslaying for years on end and has ceased to age due to intaking so much argent and demonic energy. It makes sense as to why the demons treated him as the final boss and sealed him away in the tomb in this case.

[Knee Deep In The Fan]

In regards to the new look his armor has for Eternal, the developers said there is a story reason why the armor now looks the way it does in the game.

[DoomNutts369]

The old armour looked better in my opinion i just think it fit doom guy better than the Eternal but that wont stop me from getting the game i am curious what they will do with the story.

[S_Stryker]

I like his armor in Eternal. As for the Praetor suit's origin, it definitely seems like it was largely based on UAC tech, but perhaps there were parts of the back story in Doom 2016 that I overlooked.