[Chiefspants]

The Thanos fight worked for me.

We finally saw the Mad Titan in this movie. In IW, Thanos wasn't his normal self after sacrificing Gamora, a fact seen by the way he spared Tony and the rest of the Avengers back on Earth. We never really saw Thanos lose his cool in the entire fight on Titan (the Russos said this would have happened had he lost the gauntlet - and that actually, the Avengers may have been lucky they didn't get the gauntlet off). Also, Thanos no longer felt the need to be armored up after acquiring his 2nd infinity stone. Thanos simply wasn't expecting a game-changer like Thor with Stormbreaker during the events of Infinity War.

In Endgame, Thanos is armored, fresh off of fighting, has an Asgardian weapon (wonder what happened to that by the time of IW?) and is fully in the Mad Titan mindset (Gamora hadn't yet defected). Additionally, Thanos is fighting a Thor and an Iron Man who have been out of practice for five years. Cap was really the only one who was up to the fight, and almost singlehandedly ended Thanos with Mjolner.