it would be interesting if a Jedi's kyber crystal was a more literal embodiment of their soul, the way that dragon's eldunari are in the Inheritance Cycle
they use their kyber to build their sabers, which is why it's such a huge taboo to lose or destroy them, but they keep the true nature of their kyber secret, and use the planet of Illum as their cover for 'retrieving' kyber, while the Temple there is mostly ceremonial for testing if an Initiate is mature enough to be trusted to carry their soul externally to their own body
retired and deceased Jedi pass their kyber down in the form of their saber to their lineage descendants, to carry that knowledge and experience into their futures once their mortal body is no longer capable of looking after them
Sith, however, still bleed their own souls, or else steal a Jedi's kyber to make use of their strength in their own weapon against the Jedi's will
during the Clone Wars, Grievous knows exactly what he's doing as he collects Jedi lightsabers, and delights in taunting Jedi with the tormented souls of their fallen compatriots
the lightsaber that Obi-Wan passes down to Luke contains Anakin's true soul, since Obi-Wan managed to take it from him before he could bleed it himself
