Katara's powers and abilities
Katara's most notable ability was her waterbending. She rapidly developed her skill at the art, as her fierce resolve to master the element helped her become one of the most powerful waterbending masters in her era. Katara was identified as a waterbender when she was a small child after she cracked some ice when her brother teased her. She kept practicing even though she did not have a teacher as her father could not find any, learning whatever little she could with great ambition. Over the course of her childhood, she taught herself basic waterbending techniques and managed to master some simple waterbending forms. This was a difficult feat, considering she would have never had the chance to observe waterbending in practice. As of the discovery of Aang at the South Pole, Katara was capable of "pushing and pulling" water, streaming small amounts and manipulating it into basic forms and movements, and was beginning to gain some control over the ability to change its physical state, freezing it into ice, as well as attempting to create sizable waves of water. What little she knew, she taught to Aang, who quickly mastered all she had to offer. That which had taken her years to achieve, Aang managed to imitate and outperform her within mere minutes, much to her envy and frustration.
Katara's waterbending remained amateurish until she came across a Northern Water Tribe waterbending scroll in a pirate-traders ship depicting several different traditional waterbending forms. Incapable of passing up such an opportunity to have formal instruction, she eventually made away with the scroll and first learned the water whip technique with Aang and afterward continued to improve their overall technique. Up until their arrival at the Northern Water Tribe, the two showed considerable improvement and Katara's confidence in her own abilities increased dramatically. She demonstrated the ability to bend with much greater precision and ease compared to when she first stole the scroll, was able to draw unseen water out of different sources and bend greater quantities in general, streaming them into powerful blasts and freezing water with much more control than before. She later developed several of her own techniques, including cloud manipulation with Aang's help, and a hand-held variation on the water-whip technique. She also demonstrated greater manipulation of ice and snow. In the time between her acquisition of the waterbending scroll and arrival at the North Pole, her sheer determination and discipline saw her proficiency improve greatly, clearly surpassing that of Aang's. Later, Katara challenged the master waterbending instructor of the Northern Water Tribe, Pakku, to a duel. Though she was undoubtedly no match for the master, she was determined to not be beaten. She demonstrated more advanced techniques than she ever had previously and greater proficiency in basic waterbending techniques she had previously learned. For the first time, she was seen bending with her feet and transforming the physical state of a wave. Pakku eventually removed her ability to bend by trapping her body and limbs between spikes of ice and so won the fight without harming her, though he admitted that she was an exceptionally talented waterbender. Under the guidance of Master Pakku, Katara's waterbending abilities advanced quicker than that of any student he had ever trained, which he accredited to her fierce passion and hard-work. She fought and defeated Zuko with the augmented power of the near-full moon. During the fight, she knocked him off his feet, deflected his attacks, imprisoned him in a dome of solid ice, and later a wave of solid ice. Though she was defeated by Zuko after the sun rose, she fought him again with the full moon and defeated him easily.
Katara showed promising potential of being a prominent waterbender.
Following the Siege of the North, Pakku declared Katara a full-fledged waterbending master in the short time that she was at the North Pole. She continued to hone her skills, regularly demonstrating her waterbending mastery in battle. In Omashu, she blocked a flurry of Mai's knives by waterbending wooden boards into the air as shields in front of herself, managed to block arrows with a wall of ice, and retaliated by freezing Mai's arm in ice, only being defeated when Ty Lee snuck behind her and blocked her chi, preventing her from waterbending. While in the swamp with Aang and Sokka, Katara used the stores in her pouch and caused enough pressure to the water in order to cut apart the vines, created large waves in the swamp water, froze a part of Huu's "swamp monster", created a coil of water to blast a hole into the monster and large round blades out of the water to cut up it completely. Later, she easily defeated two earthbending students by freezing them in solid ice. When facing Ty Lee a second time, she fought using the water in her pouch to fend off her chi blocking attacks, forcing Ty Lee to cartwheel away from disks of razor-sharp water. She also stopped Azula from killing Aang by catching her hand in a water whip. While crossing the Serpent's Pass, Katara made a bridge of ice for the group to travel across, worked with Aang to support an underwater bubble for the group to travel in, surfed around on a surfboard of ice, and formed a massive whirlpool with Aang to defeat the serpent.
Katara rapidly condensed water vapor into ice to defeat her foes. When assaulting Jet upon re-encountering him, she used ice spikes, similar to Mai's daggers, to pin Jet to the wall in an alley. While fighting off the Royal Earthbender Guards, she defeated dozens of them with whips and streams of water. In the Crystal Catacombs, Katara and Aang fought against Zuko and Azula, whom she managed to cut one hair bangs and created two enormous whips of water, which she used to briefly trap her. Later, these whips were able to match Zuko's enormous fire whips. When she was finally surrounded by Dai Li agents, she defended herself with the octopus form and rode on an enormous wave which knocked down these agents as well as Zuko. She proceeded to escape on a rising stream of water, carrying Aang to safety.
Katara's waterbending later became even more advanced and destructive. During a fight with a Fire Nation ship, she lifted a huge wave to separate the two ships and formed a huge steam barrier between them for cover. Once their ship was hit by a harpoon, she used her frosty breath of waterbending to freeze the hole in the ship's hull, thus repairing it. When Aang held a dance for some of his Fire Nation school friends, she created a fountain out of solid ice for beverages and the glasses they used to drink from. At the Jang Hui River, Katara created a cover of steam and sped herself atop the water's surface. Assisted by Aang, she formed crashing waves and precise missiles of water to destroy a Fire Nation Army factory. She also blasted a Fire Nation river craft into the air and against a cliff, as well as transported a huge bubble of water from a nearby creek to extinguish a fire.
When Combustion Man locked her and Toph in jail, Katara adapted to her environment, using her own sweat as a catalyst to form a water knife which broke out of a wooden prison cell. During her time hiding within the Fire Nation, Katara met Hama, an elder, yet fellow waterbending master from the Southern Water Tribe. After learning this, Hama began training her in Southern Style waterbending. Among many techniques and combat tactics, she became able to condense moisture in the air to create her own water source for her bending and could remove water from plant life. Alternatively, with the latter skill she could bend the plants by controlling the water inside them.
On the Day of Black Sun, Katara fought against the Fire Nation guards at the capital, destroying several guard towers with Sokka and defeating many soldiers. At the Western Air Temple, she rained ice spikes onto Combustion Man. While tracking down her mother's killer, Katara used the enhanced power of the full moon to nearly take down a whole Fire Nation ship of the Southern Raiders single-handedly. During her encounter with Yon Rha, she created a large wide dome of water by gathering rain drops and created ice spikes from it, nearly killing him. Katara's prowess was formidable enough to fight against such prodigious master benders like Azula. Finally, during Sozin's Comet, she froze herself and Azula into a block of solid ice, thawed the center of it, and chained Azula to a water grate.
Katara's innate aptitude toward waterbending abilities made her a rare case to naturally have access to the incredible ability to heal by manipulating the chi paths in a person's body, including herself. She inadvertently discovered this ability after Aang accidentally burned her hands and subsequently used this power again to heal Aang's own burn after his face-off with Admiral Zhao. Once she reached the Northern Water Tribe, she further developed this ability by training with Yagoda. By the time the gang met the General Fong, she healed several of his injured earthbending troops. However, Katara unsuccessfully attempted to heal Jet after he was fatally wounded by Long Feng.
With the aid of a small vial of spirit water, which held special properties, from the Spirit Oasis, Katara's healing abilities were enhanced. Though she was going to use the spirit water in an attempt to heal Zuko's scar, she instead used it to bring Aang back to life after he had been struck in the back by Azula's lightning. Even though she wasted out the Spirit Water, Katara's healing was enough to allow her father Hakoda to walk again after he was injured while taking out a Fire Nation ballista tower during the invasion. During Azula and Zuko's Agni Kai, Azula generated lightning and aimed it at Katara rather than Zuko; but he jumped in front of Katara and let the lightning shock him instead, sparing her from near death. Her healing had been successful enough that he could rise to his feet just moments after she had begun.
As an adult, Katara's prowess continued to grow, as she became well-recognized in her abilities throughout the world. She proved herself to be an excellent teacher, having trained her daughter and Avatar Korra to become highly adept masters themselves. However, even though her healing skills were recognized to be "the best in the world", she could not restore Korra's bending after Amon severed the connection Korra had to the three elements other than air with his bloodbending.
After learning all of Hama's Southern Style skills, Hama decided to teach Katara bloodbending, an advanced ability to manipulate the water within the body of all living beings, controlling them like puppets. When Katara refused to learn such a technique due to viewing it as dark and immoral, Hama decided to silence her with the said technique. Despite only just hearing about the skill, Katara showed an innate talent for the art, quickly becoming the first known person to break the effects of a bloodbender's grip and free herself. Ultimately however, Hama tricked her into utilizing bloodbending to save Sokka and Aang, leaving her greatly distressed.
When she traveled with Zuko to hunt down the man who killed her mother, Katara alone took out nearly the Southern Raiders under the full moon. After she discovered where the captain was, she let her anger take over and used bloodbending on him, which stunned Zuko. When she discovered that he was not the man she searched, she released him, shocked and dismayed that she had just used bloodbending on an innocent person. She is the only bloodbender who was never known to have had someone else break free of her grip, though she rarely used the skill. Though this was the last known time she used the technique, Katara came to greatly understand its workings, as she was able to determine how Amon had used bloodbending to remove Korra's bending, although she was not able to restore it.
Katara's weaknesses If her hands are restrained, chi is blocked, or has no water, she cannot use her bending.