Waterbending
Katara's Waterbending abilities develop considerably throughout the series. At the outset, she has little control over her Waterbending, and often loses control in moments of frustration. Thanks to diligent practice, a Waterbending scroll, and Master Pakku's tutelage, her skill improves until Pakku names her a Master.
At her full power, Katara can use water to cut through objects; summon lashing waves and whips of varying sizes; cover herself with a sheath of water; surf on a length of ice; run and stand on the surface of water; melt and control existing ice; form ice into various shapes; freeze water and objects surrounded by water with little effort; create walls of mist and steam; transform steam into ice; evaporate large amounts of water; or derive a weapon from any moisture including her own perspiration. Additionally Katara is able to bend the fluids in a human body, leaving the target unable to move or resist in any way. Although she dislikes Bloodbending, she once uses it on an enemy soldier upon mistaking him for her mother's murderer.
Katara is one of the few Waterbenders born with the sub-talent of healing, as apparent when she is burned by Aang's first attempt at Firebending; an ability improved under the tutelage of the Northern Water Tribe's healer Yagoda. She uses it thereafter to relieve sickness; overcome brainwashing; and heal seemingly mortal wounds such as burns and bleeding injuries. Nevertheless, she cannot cure all sicknesses, completely mend brain damage or heal internal injuries and birth defects. Using the water she obtained from the Northern Water Tribes Spirit Shrine, that she kept in a small pouch hung around her neck, she was able to heal a fatal wound Azula inflicted upon Aang, thus reviving him from death. She speculated that she would be able to use that same water from the Spirit Shrine to heal the scar on Zuko's face when they were imprisoned underground together in Old Ba Sing Se, however they were interrupted before she could attempt it. By the time of "The Legend of Korra", Lin Beifong (Toph's metalbender daughter) claims that she is the strongest healer in the world.
Katara demonstrates the ability to bend water-based liquids, as well as pure water, in episode "The Southern Raiders", wherein Katara bends ink onto a map. She is also seen bending soup (which allows her to cook meals), and bends perfume while battling the blind monster Shirshu. In the episode "The Painted Lady," she uses her bending to create a thick fog. Katara also demonstrates the ability to bend sweat and the ability to bend mud with Toph, who bends the earth elements while Katara bends the water.
Read more about this topic: Katara (Avatar: The Last Airbender)