You have to beat the last boss twice. One in his regular form and the 2nd time in his beast form. Bosses name is Shaher. After you beat him the first time, you get the Anbicion, which is the sword he was wielding. It is one of the strongest swords in the game with 90 pwr. But to defeat the last boss you must attack him first with the Longiculnis. After that the rest of the characters can then inflict damage upon him. He has about 600 or so hit points. And the most damage that you can do to him per turn is about 17-25. At least for me anyhow.