Padawan Obi Wan Kenobi's lightsaber-A Force Nexus
In Jedi Apprentice-The Uncertain Path, Obi Wan leaves the Jedi Order and is rendered nearly powerless as a result. Qui Gon remarks this upon observing his lightsaber
Qui-Gon's hand drifted to Obi-Wan's lightsaber, still tucked into his belt. He closed his fingers around the hilt. It seemed to hold some sort of charge, even though it was deactivated. Or was it the Force he felt, pulsing around him?
Credit: Jedi Apprentice-The Uncertain Path
That is well and good, but there is also a way to quantify how much power the lightsaber held in the force as well.
Obi-Wan reached out to the Force. He would need it in this battle. But the Force slipped away from him like an unseen sea creature that brushed against him and then moved on. He could not reach it or summon it. He could only imagine its great power.
The Force had left him.
Credit: Jedi Apprentice-The Uncertain Path
Despite being nearly powerless in the book, this is what happens when he makes contact with his lightsaber again
Obi-Wan's hand curled over the hilt of the lightsaber. As he hefted it, the Force suddenly surged through him.
Credit: Jedi Apprentice-The Uncertain Path
This also happens
They leaped up over the fountain wall and ran toward the battle. Blaster fire pinged around them, but Obi-Wan was able to deflect it with his lightsaber. With a sense of deep gratitude, he felt the Force enter and guide him. He moved without having to plan, anticipating where the fire would come.
Credit: Jedi Apprentice-The Uncertain Path
The biggest thing here is that Obi Wan is Qui Gon's padawan only for a few months here. He is only 13 years old in this book. His lightsaber is already a decently powerful nexus 12 years before TPM, which is pretty impressive when you consider that only among the most powerful of Sith Lords in history like Darth Sidious and Exar Kun have managed to do the same( although the power would vary, obviously) to their lightsabers in SW material.