Summary
- Yoda never used his lightsaber in the original Star Wars trilogy because he believed that wars do not make one great.
- Yoda saw his lightsaber as a weapon and a meditative tool, and vowed to never use it again as an act of penance for his involvement in the Clone Wars.
- Yoda chose to teach Luke Skywalker to be a true Jedi Knight without relying on combat, emphasizing the importance of selflessness over fighting.
Jedi Grandmaster Yoda is one of the most powerful Star Wars characters, but there is an in-universe reason why he never used his lightsaber in the original Star Wars trilogy. Yoda was initially introduced in The Empire Strikes Back and was the one who oversaw the bulk of Luke Skywalker’s Jedi training. During the time of the original trilogy, Yoda was one of Star Wars' oldest characters, living to about 900 years by the time of his death in Return of the Jedi. However, this meant that Yoda was one of the wisest Jedi, and over time could see where the Order went wrong.
Yoda’s lightsaber was first seen in Star Wars: Episode II—Attack of the Clones, where he faced off with his former apprentice-turned Sith Lord, Count Dooku. It was during this fight that Yoda’s skill with a lightsaber was on full display, showing the Jedi Master as a warrior. Yoda and his lightsaber would be seen again in Star Wars: Episode III—Revenge of the Sith when Yoda battled Emperor Palpatine in the Senate. However, after that duel, Master Yoda is never seen using his lightsaber again. This makes audiences wonder why that’s the case, and the answer is much sadder than some realize.
Your browser does not support the video tag. Yoda Learned Wars Do Not Make One Great 
One of Yoda’s first lines in Star Wars came in The Empire Strikes Back, where he tells Luke Skywalker that "wars not make one great." This line is better understood when knowing Yoda’s experiences in the Clone Wars. Yoda saw great warriors fall to the dark side like Anakin Skywalker, and others perished during Order 66. Though Yoda was able to escape the initial attack while fighting on Kashyyyk, he still dealt with the emotional fallout of the Jedi Order's involvement in the war. While filming The Empire Strikes Back, it was probably easier for Yoda’s puppeteer Frank Oz if he didn’t have a lightsaber, and as the galaxy grows, this decision makes sense.
It's also seen that after Yoda’s duel with Palpatine in Revenge of the Sith, he is largely non-combative. Yoda knows the danger of war and how it can be a slippery slope to one losing their way. Instead of teaching Luke with his lightsaber, Yoda challenges him in other ways—showing that Luke doesn’t need to be a great warrior to be a true Jedi Knight. It’s a lesson Yoda and the rest of the Jedi Order learned too late, but was one that was vitally passed on so Luke could rebuild the Jedi Order. When Luke's most critical moment came, he threw his lightsaber away, defeating the Emperor through a selfless act, rather than combat.
