The Yukianasa (or Yuki) is a weapon with control over ice and snow. The only costs are the loss of suiton Chakra and one's free will. The blade was created by the Yukikage, Haruto, and has had several different owners. The blade absorbs moisture from the air, water from the atmosphere, and uses chakra as a "command" to use this in whatever way the user wishes. If the user is out of chakra but the Yuki is active, then it saps the user's free will, and amplifies their emotions.
The blade freezes anything it touches in its active state, and the user can shatter it by snapping their fingers, however chakra is required to fully harness its powers and used ranged attacks.
Finally, Yukianasa alters the mental state of its owner. For example, emotions are greatly amplified, causing some to break a cold persona and making him seem violent towards the people they're usually cold or indifferent to; Or go completely insane towards those the wielder holds deeper feelings for.
Yukianasa is a sentient being, as its owners have exchanged words with the sword on several occasions. It seems as if the Yuki was talking to its wielder and giving orders the user would struggle to rebel against the orders even if even if they didn't want to follow them.
The Yukianasa erodes life, which is why "Rengoku Hyoya" is able to freeze fire and wind based ninjutsu,
The Yuki also allows the user to use one handed seals for its techniques. But ONLY it's techniques.
After recent events, the blade has become entirely sealed, and is now just a stylized normal katana. But, it can potentially be unsealed once more.
氷翔剣, Hishōken (Lit.Flying Ice Sword) The wielder performs a string of one handed seals, then points the Yuki away from themselves, firing an ice sword forward. A version moves forward slowly. In the air it has a sharp downward angle
氷翔撃, Hishōgeki (lit. Flying Ice Attack) Fires a giant ice blade on the ground or three Hishoukens in the air.
凍牙氷刃, Tōga Hyōjin (lit.Frozen Fang Ice Blade The user points the blade skyward, charges chakra into it, then slashes downwards, creating a curved, thin blade of ice.
氷翼月鳴, Hiyoku Getsumei (lit.Ice Winged Howling Moon) The user performs seals, then forms a bow and arrow of ice and shoots it upward at a 35 degree angle.
虚空刃 雪風, Kokūjin: Yukikaze (Eng. Judgment: Snowstorm lit.Empty Air Formation: Snowy Wind) The user blocks an attack, then creates a small sheet of ice, slides around the opponent quickly, and slashes with the blade.
煉獄氷夜, Rengoku Hyōya: (Lit.Icy Night of the Purgatory) Utilizing the power of manipulation over ice using Yukianasa, the user concentrates all his chakra into his sword and stabs it into the ground. A cage of ice appears to entrap the opponent. After about 5 seconds of freezing their opponent, the wielder then turns and sheathes their sword, causing the ice cage to shatter, potentially killing the opponent on contact.
霧槍 尖晶斬, Musō Senshōzan (lit.Mist Spear Piercing Crystal Slash) The wielder performs one handed seals and creates an icicle to ride on. They then leaps off to slash their opponent, impaling them with the icicle and freezing them too.
氷連双, Hirensō lit. Ice Chain Double The user draws their sword in a circular flash which freezes, then swipes their opponent to shatter the ice and send them flying.
雪華塵, Sekkajin lit. Snow Blossom Dust The wielder wildly slashes with his scabbard and sword in several directions.
裂氷, Rehhyō (lit.Rending Ice) A stationary vertically-aimed quickdraw slash that launches.
吹雪, Fubuki (lit.Blizzard) The wielder throws out a turning battoujustu quickdraw angled 45 degrees upward.