Why Anakin REALLY Lost To Obi-Wan On Mustafar
The duel between Anakin Skywalker and Obi-Wan Kenobi on Mustafar is one of the most iconic sequences in the entire Star Wars franchise. It is the point at which Anakin's fall results in the injuries that imprison him in the Darth Vader suit that we have all come to know and love. People knew that Anakin could not win, due to the existence of the original trilogy. But that does not stop people from speculating about why Anakin did not win the duel. Of course, there is the meme reason, which is that Obi-Wan had the high ground. But there may be another reason why Anakin lost the duel.
Comic Book Resources recently discussed a theory about why Anakin may have lost, and it actually makes some sense if you really delve deeply into it. When Vader first arrives on Mustafar to take out the Separatist leaders, he has the infamous Sith yellow eyes. Here is a quote that the article cited from Star Wars: The Visual Encyclopedia.
"as windows to the soul, eyes reflect the emotions harnessed by the Sith. When rage and anger seethe inside a dark side user, their eyes may burn yellow with a fiery-red rim."
When Anakin is killing the Separatists, his soul is filled with rage and anger. After all, it was Nute Gunray who tried to have Anakin's wife Padme Amidala killed time and time again, and the Clone Wars had taken a toll on Anakin, who wants to end the war once and for all. Despite having committed atrocities himself, he is probably really angry at the Separatist leaders for all of the hurt that they caused across the galaxy.
When Padme and Obi-Wan arrive on Mustafar, however, Anakin no longer has the Sith yellow eyes. He Force chokes Padme and is clearly angry at Obi-Wan, but if we abide by the rules of the aforementioned encyclopedia, Anakin does not tap into as much rage while fighting Obi-Wan as he does when he massacres the Separatists.
There are a couple of options posited for why Anakin may not have fully tapped into his dark side potential. One is that Anakin may have felt that he still had something to prove to Obi-Wan, that he was powerful even with less effort. He may have wanted to show Obi-Wan that he could defeat him even without going full throttle with all of his powers. The other option is that, deep down, Anakin may have known that everything he did was wrong, and perhaps a part of him was trying to fight against the dark during this duel and could not bring himself to kill his master immediately. It would certainly explain why the duel is so drawn out. (The real world reason is probably that George Lucas wanted it to look like a huge spectacle, if I were to take a guess.)
Anakin is certainly full of hatred after Obi-Wan left him with no limbs apart from the robot arm. In that moment, when he is crawling by the lava river, Anakin's eyes appear to be Sith yellow again. If there was a part of him that was hesitant to kill Obi-Wan, then that part of him is gone in this moment, and he wants to kill his former master but cannot do anything about it right away. His soul is consumed by the dark side, but his body is unable to utilize the potential in that moment. Maybe Anakin would have won the duel had he tapped into all this rage at the start of it.
Source(s): CBR