system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why can a Jedi wield other Jedi's lightsaber without issue?

If Lightsabers are built specifically tailor for the user alone since he/she is the one who built it; how come Jedi's usually don't have a problem being given a spare lightsaber and still use it proficiently?

 Like for instance when Obi-Wan and Anakin lost both their lightsaber in Geonosis and were given a random lightsaber yet they wield if as if they had built it themselves. Even for example Barriss was able to use Ventress's light-saber and still duel Anakin even getting the upper hand in many cases.
gpt
Where did you get the idea that each lightsaber is only usable to one Jedi? That's like saying that a gun can only be used by the person who put it together.

No, a lightsaber is just like any other weapon, anyone, Jedi or not, can pick one up and use it. The difference is only a Jedi could use one to its full potential.  That said, when a Jedi does build their own lightsaber they do so to fit their personal style of fighting as well as their own dimensions, but for the most part that wouldn't hinder another Jedi from using it.