Despite being a young demon, Nezuko has displayed great combat proficiency and skill in battle, overpowering the temple demon or the samps demon . Nezuko's accelerated growth also seems to mirror Tanjiro's own incredible growth rate, as she could take on members of the twelve kizuki and match Upper Rank demons in months. However, the trait that sets her apart from all other demons is the fact that she has the ability to conquer the sun, prompting the Demon King to call her the "chosen demon".
Abnormal Demon Physiology: As the "chosen demon", Nezuko has several unique demonic traits that set her apart from all other demons. Most notably, Nezuko can continuously restore her power without consuming any human blood like any other demon would need to do. Instead, she recovers her strength through sleep alone, though she would have to spend a lot of time sleeping in order to recuperate and regain her power. Moreover, Nezuko has an extraordinary growth rate, as shown multiple times when she grows stronger without any training or consuming humans. This ability is shown to trigger even in the midst of battle and with huge power boosts. This is best exemplified during her battle against Susamaru where her foot was blown by the Temari demon's ball attack, but after regenerating she was able to face her in an even match kicking the ball and eventually surpass her.
Advanced Demon Form: Nezuko has the ability to enter a berserk state where she becomes more demonic in appearance, transforming into an adult version of herself with vine-like tattoos that circle her body, a single horn protruding from her right forehead side. This awakened form greatly enhances Nezuko's physical capabilities as well as increasing her regeneration level to match that of the Upper Ranks'. When she first awakened this ability in her fight with Daki, she became frenzied in battle, lost her usual restrain to human blood, and the only way she could revert back to normal is to have Tanjiro sing her a lullaby. During the Demon Slayer's fight against Hantengu, Nezuko manages to control this form at will, allowing her to fight more effectively while maintaining her usual composure and restrain from feeding on humans.
Sunlight Resistance: During their battle against Upper Rank Four, Hantengu, Nezuko developed immunity from sunlight, a feat impossible for demons, even by the Demon King himself. With this immunity to sunlight, she is able to completely walk and go about in the daytime without being burnt to ash, prompting Muzan to shift his goals to hunt and absorb her to conquer the sun himself.
Blood Control: In addition to her Blood Demon Art, Nezuko has shown in her Awakened Form to have immense control of her own blood. When her limbs and head were all severed and she was going to be cut into pieces by Daki, Nezuko managed to control her severed limbs and head by instantly congealing and solidifying the blood spraying from them before the streams could break apart. With this, she was able to command her limbs to grab and stop Daki's sashes, and, even though it was done with floating, severed limbs connected by blood, she was able to do it with such strength that the sashes were stopped dead in their tracks. She was then able to pull all of her limbs back together through those blood streams, allowing her body to regenerate.
Nezuko instantly reattaching her body parts.
Immense Regeneration: As a demon, Nezuko has enhanced regenerative abilities that allow her to heal in the blink of an eye. When she first became a demon, her regeneration was relatively slow compared to other demons, taking a while to heal slash wounds. However, once in her awakened state, her regeneration ability evolved to the point it matched the caliber of the Upper Ranks, allowing her to reconnect her whole torso and body parts as well as regrow her arms and legs instantaneously. Daki noted that Nezuko's regeneration then surpassed her own.
Nezuko kicking the Temple Demon's head off.
Immense Strength: Nezuko possesses naturally enhanced physical strength as a demon. Even at the start of the series when she first became a demon, she was strong enough to decapitate another demon with a kick. Nezuko also punched the Swamp demon so hard that he coughed up blood, even overwhelming the demon with powerful punches and kicks. As she has no combat experience, Nezuko relies on brute strength, using her legs as her main weapon to deliver fast and strong kicks. Nezuko has also shown to increase her strength in battles during dire situations, like strengthening her legs to kick back Susamaru's handballs despite having her legs torn off by them earlier. In her awakened state, she could pierce through the back of an Upper Rank demon with a kick and hold down the clones of Upper Rank Four, Hantengu. She was also capable of stopping an awakened Daki’s obi with her bare limbs. This same Obi was powerful enough to wound Tanjiro Kamado and wreak massive destruction upon multiple buildings.
Size Alteration: Upon being transformed into a demon, Nezuko displayed the basic ability to change and alter her body's size and height. She was able to shrink herself into the physical size of a small child in order to fit inside a small box or a basket in order to hide from sunlight when traveling through during the daytime with Tanjiro and could enlarge herself into a much bigger form, in order to be able to battle against demons.