In KH1 Riku had Soul Eater the sword Maleficent gave him which he used in CoM. At the end of CoM Riku chose the middle path or twilight path between darkness and light. Like putting Coke and Pepsi in the same glass. You don't have a glass of Pepsi or a glass of Coke, it’s something in between. The Twilight Keyblade is called Way to Dawn (WtD). Like wise Sora and Mickey have the dark and light Keyblade. Think star wars with the blue and red lightsaber colors. Note! Soul Eater DID NOT TURN INTO WAY TO DAWN AND THE BLACK KEYBLADE IS NOT THE DARK KEYBLADE. Soul Eater is a sword and Way to Dawn is a Keyblade and the black keyblade Riku used at the end of KH1 I think is called the heart unlocker or something like that.