First off if a gm wants players with cybernetics to use lightning he can always find a way to justify it. I will withdraw my reasoning about needing flesh... but if you have cybernetics and use lightning there should be a huge change of shorting out your cybernetic arms... lol I thin now the conversation is closed!
this is from wookepedia:
Keep in mind, though, that the canonical proof for this is scant at best. All we have is a short sentence in Rise of Darth Vader saying "his arms and legs were mechanical, and he could never cast Force Lightning". It doesn't even say, "because his arms and legs were mechanical, he could never cast Lightning", so if I wanted to be really difficult, I could say that it was just a list of unrelated disabilities he had, and that his inability to cast Lightning was because of something else. And the part about him being unable to cast the power because his mechanincal limbs would short-circuit. DarthMRN 02:32, 30 June 2007 (UTC)
George Lucas has confirmed this theory, and in fact it originated from him. And although we may not like it, his word is as canon as the films themselves. So there's your confirmation. If Vader casts lightning he would short circuit his cybernetics and disable his life support 184.108.40.206 16:50, 30 June 2007 (UTC)