Editing Master's Defender

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The '''Master's Defender''' is the default form of [[Brain]]'s [[Keyblade]] that appears in ''[[Kingdom Hearts Birth by Sleep]]'', ''[[Kingdom Hearts 0.2 Birth by Sleep -A fragmentary passage-]]'', ''[[Kingdom Hearts III]]'', and ''[[Kingdom Hearts Union χ]]''. It is passed on to [[Ephemer]] and eventually to [[Master Eraqus]] and his pupil, [[Master Aqua]], and is briefly wielded by [[Sora]]. A digital simulation of the Keyblade is wielded by [[Armor of Eraqus]], while an illusory copy is wielded by the [[phantom Aqua]].

Similarly to the No Name, the Master's Defender is an ancient Keyblade from the "age of fairy-tales." Brain rarely wields his Keyblade in combat, only doing so against the Darkness entity.

Before returning to the real world in the lifeboat, Brain passes down the Master's Defender and the [[Book of Prophecies]] to Ephemer.

===Between ''Kingdom Hearts Union χ[Cross]'' and ''Kingdom Hearts Birth by Sleep''===  

At some point through unknown circumstances, the Master's Defender made its way out of Data Daybreak Town. It was passed down among the stewards of the Land of Departure, and eventually Eraqus inherited the Master's Defender and the Land of Departure's stewardship after passing his Mark of Mastery exam.

Like his erstwhile friend [[Master Xehanort]], Master Eraqus rarely draws his Keyblade. When he does fight, he is able to use the Keyblade to channel his own light magic. However, even after Master Eraqus is slain by Xehanort's hand and the [[Land of Departure]] is devoured by darkness, his Keyblade remains. After destroying [[Vanitas]], Aqua takes a comatose Ventus back to the Land of Departure, where they find Eraqus's Keyblade. Following Eraqus's prior instructions, Aqua uses the Keyblade to transform the world into [[Castle Oblivion]], a labyrinth which can only be fully navigated by herself, and hides [[Ventus]]'s body within. Although Aqua keeps this Keyblade, she does not actually wield it until after battling [[Terra-Xehanort]] and sacrificing her [[Stormfall]] Keyblade to save the remnants of Terra within him.  

The Master's Defender has a smooth, cylindrical, grey shaft that tapers outward at both ends. It has a boxy guard, made up of two small, light grey boxes and copper rod. The base of the guard connects to the grip, and both sport several small indentations lining them. The grip itself is somewhat unique in that, while most Keyblade grips are cylindrical, the Master's Defender's grip is squared. The teeth are in the shape of an "E". The "E"-shaped teeth and the square grip are likely an allusion to "Square-Enix", which Eraqus's name also references. Its [[Keychain]] is made of several simple chain links and its token is the [[Terra's Mark]] symbol that appears on Eraqus's, Ventus's, [[Terra]]'s, and Aqua's clothing.

The Japanese name of the Master's Defender, "Master Keeper", reflects that it is used exclusively by characters with the title of "Master". "Defender" can mean "guardian", which may reference its use by Keyblade Masters to guard the Land of Departure. The {{ff|Defender (weapon)|Defender}} is also a recurring weapon in the ''Final Fantasy'' series.