Darth Vader is one of the most iconic film characters in history, yet his powers and skillset were very different in the Star Wars Legends stories. Prior to Disney's acquisition of Lucasfilm in 2012, the Star Wars franchise consisted of two main works. The first was the Star Wars films and canonical The Clone Wars series from the mind of George Lucas himself, the core franchise. The second was the works of various writers and artists worldwide, dubbed the Star Wars Expanded Universe (EU).
However, after Disney acquired Lucasfilm and production on the sequel trilogy began, the studio opted to rebrand the EU so that the filmmakers of the sequels would not be constrained by specific rules and regulations introduced by the expanded material. The Star Wars EU then became Legends, the same collection as before, only now non-canonical to the core Star Wars films and the Skywalker saga. Due to this, Legends has many outlandish, incredibly ambitious storylines surrounding Star Wars characters, including the legendary Sith Lord Darth Vader, who holds unseen abilities and powers from the old Expanded Universe.
Force Destruction
The first of these powers that Vader has been shown to possess in Legends but not Star Wars canon is Force destruction. Force destruction is an ability that aligns with the dark side, allowing users to create a vast energy field that can be hurled at enemies. While this sounds similar to a Force push, which Darth Vader has been shown to exhibit many times throughout Star Wars canon, the dark side connections of the move render it much more dangerous.
As evidenced by the name, Force destruction emits a massive blast radius. This blast zone can cause anyone who comes into contact with it to vaporize instantly, differing significantly from Star Wars canon's Jedi Force push. Force destruction's power is so great that even those who avoid direct contact with the blast are blown backward by its force. Vader used this ability in the Legends stories Splinter of the Mind's Eye, written by Alan Dean Foster, and the video game Star Wars: The Force Unleashed.
Force Cloak
Another ability that Darth Vader has used in Star Wars Legends is the Force cloak power, also known as Force camouflage. Force cloak is an ability that sees the user manipulate the light and sound waves around themselves to render themselves almost invisible to the naked eye. In Legends, the Force cloak technique is often attributed to the members of the Jedi Order who utilized the power before the emergence of Star Wars' Palpatine and the Galactic Empire. After the Empire rose to power, knowledge of Force cloak was lost to the Jedi, before being perfected by a group known only as the Disciples of Twilight.
According to Wookieepedia's account of Star Wars Legends, Darth Vader used this ability on Bespin during his duel with Luke Skywalker. Vader did this to stay hidden from Luke before their duel began. However, due to Luke's power with the Force and his paternal connection to Vader, the former sensed the latter despite Vader's use of Force cloak.
Force Healing
Another Force move that has been used throughout Star Wars canon - though only in Legends by Darth Vader - is Force healing. Force healing has been seen in major Star Wars properties such as The Mandalorian and Star Wars: The Rise of Skywalker where it has been performed by Grogu and Rey, respectively. In terms of Darth Vader, however, Force healing has only been attempted by the Sith Lord in the now-Legends novel Shadows of the Empire.
In this novel, Vader attempts to heal his wounds obtained from Mustafar using the Force only by perverting the process by focusing on dark side elements such as hate and anger, instead of the Jedi's more benevolent yearning to heal. Vader discovered that the healing process worked, allowing him to breathe for a short time without his suit. However, due to the dark side's ways, Vader found that the healing was not permanent and only persisted as long as Vader kept his focus on hate and anger. Quickly thereafter, the pleasure derived from healing his body broke his concentration.
Kinetite (Force Lightning)
Kinetite is an ability from Star Wars Legends that stems from the dark side ability of Force lightning. In Legends, Kinetite allowed its user to mold Force lightning into a sphere of kinetic energy that can be thrown at an enemy. While Force lightning as it is shown in canon burns and electrocutes its victims, Kinetite acts more as a blunt force instrument and is thrown like a solid projectile against the opposition.
In Legends, again in Splinter of the Mind's Eye, Vader used this move against Luke Skywalker on the planet Mimban. However, Luke, with the aid of Obi-Wan Kenobi, uncovered a weakness with Kinetite. If the target employs the Force defensively against Kinetite, the sphere can be pushed back against its caster. Interestingly, Kinetite was described as the kinetic Force sphere by Foster in Splinter of the Mind's Eye in 1978 before The Empire Strikes Back, in which Vader arguably became iconic. Since then, a comic book adaptation of the book portrayed it more akin to Force lightning, earning Kinetite's title as a subset of the former ability.
Energy Manipulation
One of the final abilities Darth Vader possessed in Star Wars Legends is a form of energy manipulation through the Force, which interestingly also connects to Force lightning. In the Legends video game Star Wars: The Force Unleashed II, Vader battles with his secret apprentice, Starkiller, on Kamino. On either side of the battle stage, two giant pylons of electrical energy can be seen. At one point during the duel, Vader uses the Force to shoot lightning at Starkiller.
While this is similar to the Force lightning shown by the likes of Darth Sidious/Emperor Palpatine and Darth Tyranus, the difference in Legends is that Vader did not conjure the lightning. Vader instead used the Force to take control of the pre-existing electricity, simply redirecting it towards Starkiller. Given the expansive nature of Star Wars' Legends content, Vader possessed a long list of abilities. That being said, these examples are the main powers Darth Vader showcased in Legends that he has not in wider Star Wars canon.