Why is KYLO Ren's saber so unstable?
Why is KYLO Ren's saber so unstable? The technical reason behind Kylo Ren's unstable lightsaber and his crossguards is because he cracked his kyber crystal. This happened after his fall to the dark side when he “bled” his original blue crystal to red. And the impressive-looking crossguards are meant to vent the unstable crystal.
Why does Obi-Wan never get a green lightsaber?
This can be seen in the novel starwars.wikia.com/wiki/Rogue_Planet. It's because of his mastery of sorsue (sorry for my bad spelling.) Well if you want the ACTUAL reason it because in the original 3 films the Green Light Sabre didn't exist until after Obi Wans death.