Summary
Letting go of fear and fighting with skill, Jedi Kanan Jarrus defeated the Grand Inquisitor, but regrets not trying to save him.
The Grand Inquisitor materialized before Kanan, cautioning him about his limited power in shaping destiny. Despite prevailing over the Inquisitor, Kanan didn't attain moral triumph as he comprehends his potential to do more and offer assistance was not fully utilized.
The Grand Inquisitor's acceptance of death in the season 1 finale of Star Wars Rebels led to a backstory being given to him as a lesson for the Jedi. Jedi Kanan Jarrus, by letting go of his fear, fought the Grand Inquisitor with unmatched skills, ultimately emerging as the victor. Although Kanan didn't kill the Inquisitor, he also refrained from offering any assistance, a decision that would later trouble him. In a 2016 interview with Slash Film, Dave Filoni clarified that the Grand Inquisitor manifested as a guilt-induced apparition to Kanan within the Lothal Jedi temple.
"And what this apparition is warning Kanan about is the consciousness that resides within him. We touched on this briefly at the end of Season 1. Kanan subconsciously regrets not attempting to save the Inquisitor. He had no reason to, as the Inquisitor had never shown any kindness towards him. However, as a Jedi, Kanan still believes in the duty to extend a helping hand and save lives selflessly. That's why this vision is communicating with him."
Kanan emerged victorious in his battle against the Inquisitor, but his triumph wasn't just about defeating his enemy. It was also about his moral growth as a Jedi. Throughout his journey, Kanan strived to distance himself from his earlier swashbuckling ways and embraced the person he needed to become. Acknowledging that he could have done more, even in the face of the Inquisitor's heinous actions, demonstrates Kanan's determination to follow the path of a true Jedi.
Should Kanan Have Saved The Grand Inquisitor?
Kanan faced a difficult decision when confronted by the Grand Inquisitor. He followed the Jedi code by disarming himself, but did not extend a helping hand. Despite the Inquisitor's unworthiness, it is morally right for a Jedi to offer assistance. At that moment, Kanan was unaware of Darth Vader's presence, later realizing the fear that the Grand Inquisitor harbored.
Had Kanan helped the Inquisitor, it is doubtful that he would have survived Vader's wrath. However, giving the Inquisitor another chance would have posed a greater threat to the rebels if he were to be allowed to continue serving his master. Initially, helping the Inquisitor seemed like the correct choice, until it resulted in the Ghost crew being relentlessly pursued by a revenge-driven enemy.
As Jedi, they are often forced to make unimaginable choices, something that Kanan had to confront during his trial in the Jedi temple. The Grand Inquisitor, unfortunately, failed to grasp this lesson, but Kanan Jarrus embraced it and achieved Jedi Knighthood by acknowledging that fate is beyond his control in Star Wars Rebels.
Source: Slash Film