Avengers: Endgame - Why Captain America Was Able To Lift Thor's Hammer

2. The Enchantment Was Lifted

Although Thor: Ragnarok established that Thor's powers stemmed from within and not Mjolnir, the hammer still enabled the God of Thunder to amplify his power.

The original enchantment also still stands, but just as All Father lifted the inscription on the hammer in the comics for Superman, could Odin have introduced a caveat that enabled anyone to wield the hammer when its rightful owner was in peril?

Think about it. When Cap picks up Mjolnir, Thor is being decimated by Thanos. The Mad Titan is pushing Stormbreaker right into the God of Thunder's chest, and while it's not the present day Thor's Mjolnir, it's still fundamentally linked to his being. Sensing that the Odinson is in danger, and hearing Rogers' call, it's possible that Mjolnir would've deemed Rogers a suitable owner to help Thor in his hour of need.

It's a longshot, but again, it's not without precedent. The only alternative in that scenario would've been for Cap to charge at Thanos with his broken shield, which would've resulted in the deaths of both himself and the Odinson; Mjolnir had to come to Steve to safeguard reality.