If you read From a Certain Point of view, Yoda preferred Leia, because she was more serious and committed than Luke was. She would not have run off to face Darth Vader in Empire Strikes Back, because she would have seen the bigger picture, and continued her training, until she was ready.
In Empire Strikes Back, when Yoda responds, "No, there is another." Is it possible he was talking about Rey? If you watch the movies, this is answered clearly in, “Return of the Jedi” by Ben Kenobi's ghost. “The other he (Yoda) spoke of is your twin sister.” In other words, Leia Organa.
Why did Yoda want to train Leia instead of Luke? For the reasons he said. He had watched Luke growing up. Luke was too unsteady, too undisciplined, always looking at the horizon, never on where he is and too “old” meaning set in his ways.
Summary. Darth Vader's failure to recognize Leia as his daughter in Star Wars: A New Hope stems from George Lucas's late decision to make Luke and Leia siblings. Leia's Force abilities and her lack of awareness of her true identity also contributed to Vader's inability to sense their familial connection.
A Jedi needs to be a selfless servant, not an aggressive warrior. Yoda's teachings were focused on balance, both literally and figuratively. He wanted Luke to gain an understanding of the Force so that he would not be consumed with the prospects of combat.
Although there were very few Jedi left in the galaxy, Yoda initially refuses to train Luke as a Jedi, partly due to his age and mainly because he believed Luke to be too much like his father, Anakin Skywalker, in personality (reckless, impulsive, short-tempered, and hot-headed).
Star Wars Explained - A long time ago, in a galaxy far, far, away... Why didn't Yoda train Anakin Skywalker if he really thought that he was "the chosen one"? Yoda didn't want Anakin trained. He considered him to be dangerous, full of fear which could potentially be catastrophic.
Darth Vader didn't learn he had a daughter until Return of the Jedi, when he stood before Emperor Palpatine. The Emperor's power probed Luke's mind, attempting to goad him to fall to the dark side, and he discovered Leia's existence.
The four most powerful members of the Jedi High Council during the Clone Wars period were Yoda, and three of his students: Mace Windu, Obi-Wan Kenobi, and Ki-Adi-Mundi. While Mace and Obi-Wan are known to even casual fans, Ki-Adi-Mundi should not be underestimated.
We see in legends and Canon that Leia is not the most invested in her jedi heritage. Obi-Wan didn't know there was another Skywalker until Yoda said something. Luke had begun Jedi training and it was easier to focus on one Skywalker at a time. A Jedi can only have one apprentice at a time after all.
In Star Wars Legends Leia was visited by the force ghost of her father Anakin Skywalker, the man who used to be Darth Vader. It wasn't a pleasant meeting as Leia was unable to forgive him for the things he'd done no matter how hard he begged, and it was the only time she saw him.
Yoda considers Luke to be the last Jedi because he adheres strictly to the Jedi Code and does not accept unconventional training methods like those used by the "Bokken Jedi." Yoda believes that the "Bokken Jedi" have deviated from the path of the light and are heading closer to the dark side due to their aggression.
Return of the Jedi establishes that Yoda was aware that Anakin Skywalker had fallen to the dark side and become Darth Vader. When questioned by Luke Skywalker, he confided that Anakin was Darth Vader. Later, Obi-Wan Kenobi's Force ghost confirmed that Anakin had indeed fallen to the dark side and become Darth Vader.
Leia was not using the Force or was currently Force-sensitive during her confrontation with Vader. She began training as a Jedi years later. All these reasons prove my point: Vader didn't know Leia was his daughter, and felt no presence of the Force in her, as she was not currently strong with the Force.
Darth Vader acts like he doesn't even know C-3PO or R2D2. They were with him since he was a child. He did everything he could to forget his past. Also, his plating had been replaced many times, and protocol droids all look very similar.
Summary. Obi-Wan's seeming inability to remember R2-D2 in "A New Hope" was a deliberate choice to downplay the droid's arrival and avoid revealing too much too soon.
Leia and Han had three children, and they named their youngest son Anakin after Anakin Skywalker, Leia's biological father. Since Luke was the twin to spend more time with Obi-Wan in the old canon, it made sense that he, not Leia, was the one to honor Obi-Wan when naming his child.
Did Leia ever find out Darth Vader was her father?
Alderaan's princess knew she had been adopted by Bail and Breha Organa after the Clone Wars, but she had no idea who her parents were. That was until Luke Skywalker told her the truth - that he was the son of Darth Vader, and that she was his sister.
Leia's lightsaber was a blue-bladed lightsaber used by Princess Leia Organa during her time as a Jedi Padawan training under her brother Jedi Knight Luke Skywalker. Leia constructed her Jedi weapon shortly after the Battle of Endor, and utilized it in various sparring sessions with Skywalker.
With Yoda's presence in the Force cloaked, there really wasn't any way for the Empire, Darth Vader, or Vader's Inquisitors to find the Jedi master. Another potential explanation is the planet Dagobah itself.
Summary. Mace Windu denied Anakin the rank of Jedi Master due to his unorthodox Jedi upbringing and the Council's hesitation to promote him at a young age. Anakin's closeness to Palpatine played a role in the Council's decision, as they used it to assert their independence from Palpatine's influence.
