On Star Wars Rebels, Ezra Bridger's path to becoming a Jedi wasn't a traditional one, having trained in a post-Republic world where the group was despised and hunted. Even his mentor, Kanan Jarrus, wasn't a typical Jedi Master, being that he was still a Padawan himself when he decided to train Ezra. It's no surprise then that Ezra's original lightsaber was as unconventional as its owner. However, as Rebels progressed, Ezra found himself with a different lightsaber, with the change reflecting how he'd grown over the course of the series,
In Season 1 of Rebels, Ezra was a practical, street smart kid who knew what it was like to be alone in a place where survival is for the fittest and smartest. The blaster saber reflected this perfectly. Although Ezra had no access to traditional Jedi ways of building a saber, he constructed his weapon out of specific parts collected from other members of The Ghost. Ezra was also aware of his weaknesses, which get reflected in the lightsaber. He knew he lacked the skill to deflect blaster fire with his blade, and so he made the stun capability a vital addition to the hilt.
While a Jedi would, traditionally, never construct a saber like Ezra's, as they looked down on blaster usage, a kid used to getting the most out of every little thing and who valued survival over traditions definitely would. The blaster saber also showed Ezra's understanding that a weapon that obviously looks like a lightsaber would draw unwanted attention from the Empire, and so it helped him keep a low-profile.
However, the blaster saber didn't remain Ezra's weapon for all of Rebels. At the end of Season 2, the weapon met its end in a duel with Darth Vader. When the time came to build a new lightsaber, Ezra was maturing as a person, and the traditional look of his second saber reflected that growth. Just in terms of design, Ezra's new lightsaber no longer had a stun blasting hilt, as his skills had improved substantially.
It's not just the design of Ezra's lightsaber that changed. In Star Wars, every lightsaber color has a meaning. Ezra's original saber was powered by a blue kyber crystal. Typically associated with Jedi Guardians, blue blades are common and represent righteousness as well as bravery. Like other Guardians, Ezra spent a lot of time in combat with his blaster saber. His new saber, however, was powered by a green kyber crystal. The change in color was indicative of his change as a person, being that green blades often symbolize wiser Jedi, like Yoda, who value harmony over combat. When Ezra's lightsaber changed, the street urchin from Lothal's growth into a Padawan became clear.
Though Ezra's blaster saber might not be a weapon for a traditional Jedi, Ezra was never a stereotypical Jedi Knight. He, like Ahsoka Tano, challenged conventional thinking on who the Jedi were supposed to be. Ultimately, the lightsaber blaster was the ideal weapon for a young Ezra Bridger, but by the time it was destroyed, it was no longer necessary for who he'd grown into since Rebels Season 1.