The Jedi Order is both a military unit and a religious sect, which means they are absolutely packed with rules and regulations. From fighting to falling in love, every aspect of a Jedi's life is controlled, but one rule that sparks some interesting discussion for the organization is the requirement that Jedi personally craft their own lightsaber.
The lightsaber was first introduced early on in the very first Star Wars film, but their construction was first conceptualized in a deleted scene cut from Return of the Jedi. The process has been depicted in shows such as The Clone Wars and games like Jedi: Fallen Order.
The process of a youngling graduating to the rank of Jedi Knight is a long and arduous one, with many wide-ranging tasks and unique challenges. One of the many tasks thrust upon force-sensitive children who have been taken in by the Jedi Academy is The Gathering. This ancient ritual taught younglings to face their fear, trust their instincts and find their calling in the force. The Gathering was one of the first rituals of the Jedi Order, existing for thousands of years and becoming a crucial aspect of the road to Knighthood. Once a youngling had their lightsaber, they could train in combat and, in time, become a Padawan apprentice and begin to shadow a Jedi Knight until the time came to earn their own rank. The process of The Gathering was dangerous and unique, but necessary for the Jedi Order.
The Gathering is a process wherein six to eight younglings are taken to a barren frozen planet called Ilum. Once there, they must find their way into an ancient Jedi temple, navigate its icy waterfalls, and descend into the powerful catacombs of the planet's crystalline caves. Within the caves lies a mystical presence known as a Vergence. This Vergence is a naturally occurring concentration of force energy that gives bizarre effects to its surrounding area (Anakin Skywalker was a living example). The cave, empowered by the force, identifies the youngling's weaknesses and fears and forces them to confront them. If a student is able to face what scares them, they will feel the pull to a single crystal of the infinite amongst the caves. This kyber crystal is the power source for the lightsaber, a tiny piece of naturally occurrent translucent rock that individually reaches out towards its wielder. A youngling who has acquired their kyber crystal can now begin building its housing.
Once The Gathering is complete, younglings can begin the process of constructing the lightsaber itself, under the watchful eye of a skilled teacher. Professor Huyang is a droid who, for thousands of years, led younglings in the technical process of assembling components to form a lightsaber. He seems to be the only being in the galaxy capable of giving this lesson, and though he is unable to use the force, he is able to guide generation after generation to success. The process requires Huyang's unique voice and exclusive technical knowledge, combined with the use of the force. When depicted on-screen, it usually appears as the youngling focusing intently and the weapon being assembled telekinetically.
There are many logical reasons why each Jedi must assemble their own lightsaber. One obvious answer is simple tradition. Jedi is a religion, after all, and most organized religions come complete with countless rituals which become culturally important. Jedi have been assembling their own weapons for over a thousand years, yet have remained so devoted to the proper performance of the task that it has been overseen by the same droid since the beginning. Deviation from this tradition would likely be seen as heresy by most members of the Order, before regarding the important lessons learned in the process.
Another reason to place the responsibility on the wielder to craft the weapon is for discretion. If only one droid and the weapon's wielder know how to create the lightsaber, it prevents the possibility of others using it against the Order. Enemy factions like the Mandalorians have created numerous workarounds for battling lightsaber users, but don't seem to be able to craft the lightsaber for their own use. Blasters are fairly standard issue in the galaxy, but lightsabers are extremely scarce, only one or two per Jedi. Mass-producing the Jedi's strongest weapon would be counterproductive and would only serve to weaken their power in the galaxy.
The most important reason that a Jedi must forge their own lightsaber is to forge a bond with their weapon that can never be broken. Each youngling is granted freedom to design their lightsaber however they like, its color is decided by the kyber crystal's unique hue and there are countless modifications and special forms that the designer can make use of. Much like ancient warriors named their weapons or modern soldiers affirm "many like it, but this one is mine," the Jedi Knights go through a supreme ordeal and embrace their creativity to craft the perfect weapon. For ancient tradition, arcane secrecy, and crucial commitment, the Jedi must create their own lightsabers.