Ultima Weapon

The Ultima Weapon (アルテマウェポン) is a Keychain for Sora's Keyblade which appears in Kingdom Hearts, Kingdom Hearts: Chain of Memories, Kingdom Hearts II, Kingdom Hearts Re:coded, and also for Terra's, Ven's, and Aqua's Keyblades in Kingdom Hearts Birth by Sleep. It is the most powerful Keychain, and requires an incredible amount of effort to obtain in all four games; in Kingdom Hearts and Kingdom Hearts II, it is the final recipe in Item Synthesis, in Kingdom Hearts: Chain of Memories, it can only be found randomly in a chest after clearing both stories, and in Kingdom Hearts Birth by Sleep, it is the reward for the final match in the Mirage Arena, the Villains' Vendetta. Unlike other Keychains, each game's version of the Ultima Weapon has a different design, and shares only the name and the phenomenal quality of its stats.

Design
The Ultima Weapon Keyblade is named after the eponymous sword in the Final Fantasy series. The Ultima Weapon is typically shown within the Final Fantasy series as a long sword, with a glowing blue/white blade and a golden handle. It is usually the strongest weapon for the main protagonist in the games it appears in.

The Kingdom Hearts version of the Ultima Weapon is strongly reminiscent of the Dream Sword, but is wrapped in an ornate gold filigree in a pattern slightly reminiscent of fish bones. The teeth of the blade are a golden version of the crown charm Sora wears, and the Keychain token, attached to the blade by shimmering thread, is a gilded heart, used throughout the series to refer to a complete being, instead of a Heartless or Nobody. It also bears one heart just above the guard and another just next to the crown making up the teeth of the blade, both of which are present in the Kingdom Hearts II version. In the game, the blade's size is smaller compared to the hilt, compared to its design in the official artworks.

The Kingdom Hearts II version retains most of its Kingdom Hearts version elements, except for the colors (blue, white and gold), the crown-and-heart keychain, and the Dream Sword. It also includes many more crowns into its design, including one at the tip of the blade, near the crown "teeth", two making up the guard, three in the chain, and the aforementioned combination of a crown and the original heart Keychain as the token.

The Kingdom Hearts Birth By Sleep version has elements from both previous Kingdom Hearts games. Its style is similar to the Kingdom Hearts version, but its color scheme is similar to the Kingdom Hearts II version. It also uses stars and the Wayfinder design instead of crowns and hearts. It is mostly a pale, almost glowing blue with white and gold. The teeth and Keychain are a blue Wayfinder similar to Aqua's.

Kingdom Hearts
Ultima Weapon can be synthesized once the fifth list is unlocked.
 * 5 Lucid Gem
 * 5 Power Gem
 * 5 Thunder Gem
 * 3 Mystery Goo
 * 3 Gale

Kingdom Hearts Final Mix
Ultima Weapon can be synthesized once the sixth list is unlocked.
 * 5 Thunder Gem
 * 5 Mystery Goo
 * 3 Mystery Power
 * 3 Gale Stone
 * 3 Dark Matter

Kingdom Hearts II
The Ultimate Recipe is found in a chest at the Mansion: Basement Corridor. The Ultima Weapon is a rank S synthesis item that provides 119 EXP. An Energy Crystal is required to reduce the Orichalcum+ required for synthesis, as there are only 7 in the game; this means that the Ultima Recipe cannot be synthesized unless the Moogles are at least level 2. However, if the player should not be able to find an Energy Crystal, they can keep synthesizing until their Moogle level reaches level 9. At Moogle level 9, all S rank items hgave their synthesis costs halved. Theoretically, if the player was both Moogle level 9 AND had an Energy Cystal, you could cut the cost to 4 Orichalcum+. However, should this work, there would be no use for the other three that are left. As Serenity items are part of the recipe, they cannot be used to upgrade it.
 * 13 Orichalcum+
 * 1 Orichalcum
 * 1 Mythril Crystal
 * 1 Dense Crystal
 * 1 Twilight Crystal
 * 7 Serenity Crystal

Gameplay
In Kingdom Hearts it is the strongest Keyblade in terms of strength and MP, but in Kingdom Hearts II it is second in strength to the Fenrir and second in magic to the Fatal Crest. In Kingdom Hearts II Final Mix, it is third in magic to Winner's Proof. However, its MP Hastega ability is much more useful in normal combat than the abilities attached to these other Keyblades, making it a good choice for magic users and physical combat alike. In Kingdom Hearts Birth By Sleep, its physical strength is second to Void Gear and Crown Unlimit and third to Terra's Chaos Ripper, and is equal to Aqua's Master Keeper. Its magic strength is surpassed by the No Name, Brightcrest, Crown Unlimit, and Master Keeper, and equaled by the Pixie Petal.

Other appearances
Both the Kingdom Hearts and the Kingdom Hearts II versions of Ultima Weapon were released with three other Keyblades in a special Play Arts Figures accessory set, Play Arts Arms.

Through the use of a cheating device, two palette swaps of the Ultima Weapon can be obtained in Kingdom Hearts II. These are the "Edge of Ultima", a version of the original Ultima Weapon with a glitched appearance, and the "Detection Saber", a palette swap of the original as well, except slightly larger. When these Keychains are accessed in Sora's Items menu, no picture of the Keyblades are shown, only map icons.