Although he was one of the most formidable Jedi Masters during Star Wars' prequel trilogy, Mace Windu should have been the last one to confront Palpatine during Star Wars: Episode III - Revenge of the Sith. Despite his status as one of the leading of the Jedi Council, Windu carried key weaknesses that put him at great risk when facing a Sith Lord, particularly one as powerful as Darth Sidious. It's probably why his duel with the corrupt chancellor led to his likely demise at the end of the Clone Wars just before the dawn of the Empire.
In Revenge of the Sith, Anakin Skywalker reports Palpatine's identity as a Sith Lord to Windu. Instructing Skywalker to stay at the Jedi Temple, Windu assembles a team of fellow Masters to help him arrest Darth Sidious, the Sith Lord who'd been orchestrating both sides of the Clone Wars from the very beginning. However, Mace quickly becomes the last Jedi standing. While Windu intended to arrest Palpatine, he eventually comes to the dark decision to murder Sidious instead, a very non-Jedi reaction from a Master so dedicated to the doctrines of the Jedi Order. However, Windu's preexisting struggles with darkness should have kept him away from the Sith.
Mace Windu Was Too Close To The Dark Side To Face Palpatine
As confirmed in the established Star Wars canon, Mace Windu was an extremely disciplined Jedi Master who relied on the doctrines of the Jedi Order with very little deviation. Any Jedi who bent the rules and were considered mavericks, such as Qui-Gon Jinn or Anakin Skywalker, were generally looked down upon by Windu. However, they still had his respect for their skills.
In Star Wars: Episode II - Attack of the Clones, Windu was initially adamant that the Jedi were supposed to be peacekeepers rather than soldiers for the Republic (whom he felt the Jedi Order had grown too close with). However, Mace eventually came around to the idea of leading troopers into battle, rationalizing that the dire circumstances of the galaxy had forced the Order to become more proactive out of necessity. However, his own struggles might have aided in that rationalization. While Mace Windu was one of the most formidable warriors in the Jedi Order, he employed his own variation of lightsaber Form VII to focus a constant inner darkness.
In its original form, known as Juyo, Form VII is one of the most aggressive forms of lightsaber combat, banned by the Jedi Order and employed by dark side s such as Darth Maul. This is because it relies on unchecked emotions such as anger and ion to fuel incredibly powerful strikes, making the style intrinsically opposed to the doctrines of the Jedi Order. However, Windu developed Vaapad, an approved variation he developed himself where his own darkness could be carefully channeled and focused. That being said, it wasn't a form he was willing to teach to others aside from his own apprentice, Depa Billaba, due to its risky nature.
Mace Windu's Weaknesses Explain Why He Failed In Revenge Of The Sith
Just like his use of Vaapad, Mace Windu relied on the doctrine and rules of the Jedi Order to keep himself and his inner darkness in check. As such, he shouldn't have faced a Sith Lord like Palpatine who would logically be able to goad the Jedi Master into losing focus, becoming more aggressive than a Jedi ever should. After all, the reveal of Palpatine as Darth Sidious confirmed everything Mace Windu had been concerned about for years. The Jedi Order had been deceived and used as puppets, and all because of its closeness to the Republic which Mace had always believed was problematic.
Mace Windu's decision to kill Palpatine proves his darkness was no longer in check. Although it probably would have been the right decision for the sake of the entire galaxy, it wasn't the way of the Jedi, which Mace normally would have never deviated from. In the end, giving in to his darker nature led to Mace's demise at the hands of both Anakin Skywalker and Darth Sidious in Revenge of the Sith. Despite having turned them into a typical strength, Mace Windu should have been the last Jedi to face Sidious due to his own weaknesses established in the Star Wars continuity.
