It should be noted that Darth Vader, despite being a powerful Sith Lord, was unable to generate or deflect Force lightning. This was due to his cybernetic implants, and any attempt by Vader to generate it would cause it to backfire, electrocuting his life-support systems, causing it to short-circuit and kill him. This is ultimately how he was killed, as his act of redemption in saving his son caused him to be bombarded with the Emperor's lightning. Due to the fact that Vader's Sith powers were limited because of his artificial limbs, Darth Sidious found him less than satisfactory as his heir to the Sith legacy, despite the effort Sidious spent for more than a decade to recruit Skywalker. Upon the discovery of Luke Skywalker, Palpatine concentrated on turning him to the dark side.
by the way, the name's depressis.