Anakin Skywalker was already one of the most powerful Force users before succumbing to the Dark Side and becoming Darth Vader. As Vader, he honed those skills to allow him to manipulate energy by creating and hurling balls of Force lightning (known as Kinetite) at his enemies as seen in the Dark Horse Comic Splinter of the Mind’s Eye, Chapter 12 (by Alan Dean Foster):
He can also utilize such power for defense as well, as he’s able to create a force field made of pure energy to deflect any enemy assault. (We witnessed that ability in The Empire Strikes Back, as Vader was able to deftly deflect the laser bolts Han Solo fired at him on Bespin.)
Other notable powers stem not from Vader himself, but from his suit; enhanced strength, visual acuity, and survivability.