DominicCobb said:
Just means he knows an ability Vader does not.I wouldn’t even say “knows” as it implies it can be learnt. Emperor simply has an extremely rare given ability/potential that Vader does not. It is like getting an impossible mutation of an eye that allows eagle eye quality sight. Those who don’t have such mutation simply cannot have that kind of sight ability, not matter how hard they may try to “train” their eyes.
Yeah the Emperor was just born with the right kind midichloreans to use Force Lightning and Anakin wasn’t it’s a simple concept.
Yeah that seems a bit too biological which is the reason he doesn’t the fact Leia is Force Sensitive.
EDIT:
A simpler reason is to assume that The Emperor is the evilest and bestest Sith to have ever existed and that’s why he can use Force Lightning and that’s why his eyes are yellow. He is that evil.