Hidden Keyblades:
In Kingdom Hearts there are 19 versions of the keyblade. 3 of these are hidden, but they all make apearances in the game at a certian point.
Sora's Weapons:
Kingdom Key Metal Chocobo
Jungle King Olympia
Three Wishes Lionheart
Crabclaw Lady Luck
Pumpkinhead Divine Rose
Fairy Harp Oathkeeper
Wishing Star Oblivion
Spellbinder Ultima Weapon
Anti-key Lost Heart
Final Key
Hidden Keys:
The First of the hidden key is seen in Neverland. If you remember the fight with Antisora, you'd notice that he was fighting with a black version of the Kingdom Key. This weapon is called the Anti-Key. To aquire this weapon, unlock all of the chests in Neverland, Aquire all 12 of the hidden items from the clock tower, and defeat the Phantom at the clock tower. Return to Traverse Town and go to the Secret Waterway. Go to the mural with the picture of the moon to aquire the Anti-key. The Anti-key's stats are ATK: 10 STR: +8 MP: -1
The Second Hidden Key is seen in the Hollow Bastion. During your second fight with Riku, you'll see he's using a new Keyblade. To aquire this keyblade you must unlock every trinity in the game. There are 46 trinities total. And you must have sealed the Hollow Bastion. Go to the Secret Waterway and aproach the mural of the moon. You will then recieve the Lost Heart. The Lost Heart's stats are ATK: 11 STR: 9 MP: +1
The third and strongest key is only shown after you have beaten the game. When you beat Ansem for the final time, you see Micky holding a key that looks just like the kingdom key, except the gold and silver colors are reversed. The only way to get this key is to 100% the game. To do this, you must Lock all worlds, open all chests, unlock all trinities, Obtian all weapons, beat all bosses (hidden and regular), compleat all tasks in the 100 Acre Wood, and win every competition with your party, alone, and on time trial.
Now you just go to the mural of the moon and you will obtain this incredible weapon. The Final Key has the stats ATK: 13 STR: +10 MP: +3
there are all three of the hidden keyblades including the anti-key my favorite keyblade