The No Name, also known as Master Xehanort's Keyblade (マスター・ゼアノートのキーブレード, Masutā Zeanōto no Kīburēdo?) and The Gazing Eye (見つめる目, Mitsumeru Me?), is the default form of Luxu's Keyblade that appears in Kingdom Hearts Birth by Sleep, Kingdom Hearts 3D: Dream Drop Distance, Kingdom Hearts χ, and Kingdom Hearts III. It was handed down over time, becoming the most ancient surviving Keyblade, and eventually came into the possession of Xehanort, who continued to wield it when he became Terra-Xehanort. A digital simulation of the Keyblade is wielded by No Heart, the Mirage Arena simulation of Xehanort. It is also utilized by the replica incarnation of Terra-Xehanort.
Kingdom Hearts χ Back Cover
The Keyblade was given to Luxu by the Master of Masters when he received his assignment. The Master had placed his own Gazing Eye within the blade, granting him the knowledge of anything the eye would observe throughout the ages. Luxu initially misunderstood the Master's explanation as the Keyblade being named the "Gazing Eye", but when the Master clarified that the Keyblade had "no name", Luxu playfully named it accordingly. In order to spread its purview and write the Book of Prophecies, he assigned Luxu and the Keyblade the role of leaving town with a mysterious chest, becoming a neutral observer to the events that would soon rock Daybreak Town, and passing down the Keyblade to his own apprentices so that it would survive through the ages.
Kingdom Hearts χ
When Foreteller Ava tracks Luxu down and accuses him of being the traitor sowing discord between the Unions, he brandishes the Keyblade at her.
Between Kingdom Hearts χ and Kingdom Hearts Birth by Sleep
Kingdom Hearts Birth by Sleep
Master Xehanort does not often draw his Keyblade, but when he needs to engage in battle or use the Keyblade's powers, he uses this Keychain to do so.
When Terra, Ventus, and Aqua confront him at the Keyblade Graveyard, Master Xehanort transforms his Keyblade into an orb of light and uses it to reveal Kingdom Hearts floating above. Afterward, he uses his blade to battle Terra and trick the youth into embracing darkness, allowing him to extract his own heart and possess Terra's body. This gestalt being, Terra-Xehanort, retains usage of this Keyblade and wields it against the Lingering Will at the Keyblade Graveyard and Aqua at Radiant Garden. When Terra's heart begins throwing off Xehanort's control, Terra-Xehanort is forced to use this Keyblade on his body in an attempt to rid himself of Terra's heart. 
Between Kingdom Hearts Birth by Sleep and Kingdom Hearts
Kingdom Hearts Re:coded
Following his revival, Braig speaks with the time-traveling Young Xehanort about Master Xehanort's plans. Over the course of this conversation, Young Xehanort mentions that this Keyblade is the most ancient Keyblade of all.
Kingdom Hearts 3D: Dream Drop Distance
In order to prevent Riku from rescuing Sora, Master Xehanort possesses his younger self and wields his Keyblade with a different Keychain. Once Master Xehanort has completely revived, he wields his Keyblade personally with its traditional Keychain, and attempts to place a fragment of his heart inside Sora's comatose body.
Kingdom Hearts III
Master Xehanort uses the No Name during the final battle to fend off Sora and Riku from interfering with his ascent to Kingdom Hearts and forming the χ-blade. Terra-Xehanort also wields the No Name, first at the Graveyard's entrance in order to confront the Guardians, and later within the labyrinth against Sora, Ventus and Aqua, fight in which he teams up with Vanitas.
Each clash of the seven guardians of light with the thirteen seekers of darkness creates a replica of the No Name around Master Xehanort's high spot over the labyrinth, of which thirteen are needed in order to forge the χ-blade. By killing Kairi and provoking Sora's rage, he causes a last clash between Sora and himself, thereby creating a thirteenth No Name and turning his own into the χ-blade. Later, he summons this Keyblade within Scala ad Caelum upon assuming his armored form. Xehanort discards it in favor of the χ-blade for his final fight against Sora.
The No Name has a dark black handle with a raised spiral carved around it. Its pommel and guard resemble black, demonic wings. The base of the blade is an etching of a goat,[please confirm] and the shaft is formed from two black, barbed blades, etched with a white icon resembling a bramble of thorns. The teeth are formed in the shape of a demonic wing, and are set with the Master's Gazing Eye. Unlike the Keyblades of the Master of Masters' other apprentices, it lacks Terra's Mark. The Keychain is made of small, grey links, and the token is an entangled, grey talisman with an additional Gazing Eye.
The Keychain can take the form of a core for an impenetrable barrier, a claw-like weapon, a greave, a pair of wings that allow flight, or an orb of light.
Master Xehanort wields the No Name against Terra, Aqua, and Ventus.
Notes and references
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