Mace Windu’s purple-coloured lightsaber is unique in the films. When it first appeared on-screen, many fans were excited by this never-before-seen colour. Speculations started about what was George Lucas’s intention in introducing this new colour (after blue and green in the original trilogy) and what deep significance did it have.
The answer was simple: none. Samuel L. Jackson simply asked Lucas whether he could have purple because it looked badass. And because Mace Windu was supposed to be a Jedi of importance, Lucas granted that wish.
For Special Individuals
It served the purpose of singling Mace Windu out from among the rest of the Jedi Masters. Now he was made more special, more memorable. Compare him to, say, Ki-Adi-Mundi (the bearded guy with prolonged head) and imagine if their lightsaber colours had been reversed. You would likely pay considerably more attention to Ki-Adi-Mundi while Windu would lose some of his uniqueness.
The colour underlines Windu’s importance, and that is only well and good. He is supposed to be nearly on par with Yoda. He is a master duelist who is able to fight Palpatine alone – and he would have defeated him if not for Anakin’s intervention.
Mace Windu’s Story
Given how significant part of Windu’s character his fighting skills are, there is no surprise that his lightsaber was given great importance in the lore. Stories from the old canon tell of how Mace acquired his lightsaber crystal. Not on Ilum like most of the younglings. Young Mace requested a special challenge for himself and went alone to the planet Hurrikaine, where he acquired the amethyst-coloured crystal he later used.
Using his lightsaber, he developed (or rediscovered) a special fighting style, the so-called “Form VII” or Vaapad. This style was very effective but also risky because of its aggressiveness. As we know, the Jedi tried to fight without emotions, especially without aggression, but Vaapad led its user “through the penumbra of the Dark Side”. Only someone with a truly balanced mind was able to maintain control while using this style.
Perhaps this balancing on the verge of the Dark Side is reflected in the purple colour that is, after all, a mixture of blue and red.
Who Else Besides Windu?
There are only a handful of purple lightsaber wielders besides Mace Windu. In the times of the Old Republic, there presumably were more. In the current canon, the one character with a purple lightsaber is the recently revealed Mirialan Padawan Vernestra Rwoh from the High Republic novel series.
In the old Star Wars legends continuum, there were a couple of more important characters. One of them was Jaina Solo, the daughter of Han and Leia. Her character could be in the broadest sense compared to Rey in the new canon, but there were elements of Kylo Ren in her as well (even though there were more in her twin brother Jacen). Most importantly, Jaina had gone through periods of being tempted by the Dark Side in her life and used it a couple of times while managing to maintain self-control in the end. Perhaps we may find the similarity to Mace Windu there.
The second notable character was An’ya Kuro, dubbed “Dark Woman”. She was the master of the abovementioned Ki-Adi-Mundi but also of A’Sharad Hett, a Jedi who, in the old canon, left the order and eventually became a Sith lord. Her training also took her apprentices to the very edge of the Dark Side – in an attempt to push the Jedis’ limits, but the apprentices did not always return untouched by the darkness.
Touching The Darkness
From this, we can already make some conclusions about the purple lightsaber wielders. They are individuals who are not afraid to test their (and others’) potential to the limits, even if it threatens to cross the boundaries of the Dark Side. These masters, however, manage not to fall over the boundaries thanks to their immense self-discipline.
Purple lightsaber wielders are stricter and more orthodox than green lightsaber wielders, but more experimental than the blue wielders. But while green Jedi may treat authority loosely or experiment on a whim, purple’s way of pushing the boundaries is the result of strict discipline and the knowledge that they can dare to push.
If we put that on the traditional roleplaying scale, blue is lawful good and green is neutral good, then purple is closer to lawful neutral or even true neutral. Purple Jedi are not any less “good” than others, but they sometimes venture to places others may not be willing to go to – just like Windu exploring a new fighting style or Jaina Solo using Dark Side powers.
Purple is not for everyone – in all possible ways. Purple wielders’ colleagues may respect and admire them, but they may warn their Padawans: “Don’t attempt what Master Windu is doing, you most likely lack the strength and self-discipline to play with fire.”
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