Darth Vader Vs. Palpatine: Who Won Their Secret Lightsaber Battles?
The relationship between Emperor Sheeve Palpatine (Ian McDiarmid) and his Sith apprentice Darth Vader (James Earl Jones) is complicated to say the least. From the time that Anakin Skywalker (Hayden Christiansen) was ten years old, Palpatine preyed on the boy's erratic emotions to win the so-called "Chosen One" to his side – using guile, political savvy, and the offer of immense, death-defying power to eventually convert Anakin to the dark side of the Force.
Despite throwing away his entire life in order to join Palpatine (and destroying the Jedi Order in the process), the relationship between master and apprentice was always strained by the fact that one day, according to the Sith "Rule of Two," either Vader or Palpatine must die by the other's hand to make way for another Sith Lord to take their place. In fact, the pair actually dueled in secret on more than one occasion, with their first canon lightsaber battle coming in Marvel Comics' "Star Wars (2020)" #25, which was released in July 2022.
This battle occurred in the Works District of Coruscant, and was merely a sparring session between the master and apprentice – which ended with Palpatine easily defeating and disarming Vader, telling him he still fights "like a Jedi." It's worth noting that the events of "Star Wars: Revenge of the Sith" were still pretty recent in the comic, and this succinct defeat could be explained as Vader not being used to his new bulky cybernetics.
For now, Vader seems unable to match Palpatine's skill
The Sith master and apprentice would spar once again in the comic book "Hidden Empire" #4, released in March 2023. This time their sparring match coincided with the revival of an ancient Sith lord, with Palpatine promising to enforce the "Rule of Two" and execute Vader if necessary. Once again Palpatine is shown to easily outmatch Vader, throwing his apprentice off guard and then turning his back and telling Vader the match is over.
Vader even has an opportunity to kill Palpatine at this point, but obeys his master's command and simply shuts off his lightsaber. Although Palpatine handily won both of these secret lightsaber duels, it would be dishonest to say that he was truly more powerful than Vader, particularly because we know that Vader has the potential to defeat Palpatine if he turned back to the light side. In the canon comic book series "Darth Vader (2020)", Vader is given a vision of what would've happened if he had chosen the light side –- and within this vision he is shown swiftly defeating Palpatine and striking him down.
Because we've also seen Palpatine lose in a duel with Jedi Mace Windu (Samuel L. Jackson), it's likely that the Jedi Anakin Skywalker might have actually been able to defeat and kill the Sith Lord, but Darth Vader (at least early on in his reign) was unable to best his Sith counterpart after embracing the dark side. Although both Darth Vader and Emperor Palpatine are shown to be incredible swordsmen and display an unprecedented level of power in the force, fans haven't seen Vader match up to his master in a lightsaber duel.