Reiterating Doomguy’s skill.
This is the same Doomguy from previous games. Taking down hordes that have previously wiped out entire platoons of trained marines with access to weaponry that could have easily teared apart said demons.
He has dealt with stronger opponents before with blows that would have 1 shotted him. Most notably are the Icon of Sin (original), Cyberdemon (with a 10 meter blast per rocket), Spider Mastermind (the leader of hell’s invasion with chaingun fire that would have shredded the marine easily).
Due to the massive hordes of demons he has fought,he has dodged 10’s if not possibly 100’s of projectiles. Especially the hellish levels that were plutonia and tnt.
These projectiles included rockets,fireballs,and bullets.
Revenant’s Rockets: Homing rockets that traced the Doomguy’s place of existing.
Archville Flames: Big walls of flame that also home into the doomguy.
Teleportation: Due to little changes to how Archvilles function within lore,Archvilles in eternal teleport around him. Blocking his shots with a shield strong enough to block the BFG.
Now then,since this is the Night sentinel incarnation of the marine. He would have all this experience 3x more.
He has now defeated an entire arena of Night sentinels. Warriors who exist within a society who has only known war. With their experience in combat having been taking down Ancestrals, the predecessors of the Titans without mechs. These men are hardened and strong warriors who were vastly above the physical strength the marine was capable right after being captured. His power reacted to their strength,his will matching theirs and pushed through their ranks despite these warriors having years and years of swordsmanship training.
Now part of the sentinel army,he went through a process that was considered an execution for these warriors. Enduring the swarms of hell in which countless Night sentinels died in.
With now the demons physically comparable to him,this would have been a challenge all by itself. However he had shown such prowess that he was deemed worthy of the swordsmanship skills the night sentinels had been acclaimed for. After years of training, he ascended through the ranks and had become akin to the warrior kings. With Hugo saying the red patch within is armor being a sign of high rank.
Now after all a civil war broke out in Argenta. With fellow sentinels warrior against each other, this included the high ranking
Marauders (the human versions). Warriors who were leagues above the average night sentinel,who were impressive on their own right.
He would have had to fought Night Sentinel Archers who are praised for their marksmanship skills. Just a battalion of these warriors were capable of defending an entire fort for 10 days and nights straight from the hordes of hell.