If you have obtained and have at least one use left on the following weapons, you will unlock three extra chapters, revealing the TRUE ending of the story. Durandal Armads Malte Miruge Aurelora Apocolypse Forblaze Holy Maiden Sealed Sword
You also have to Fa, the Divine Dragon alive at the end of chapter 22, "The Neverending Dream." In these chapters you fight Brunya, Yahn, and Idoun.
To unlock certain chapters ([chapter nimber] X ) you must meet certain requirements. These chapters contain "S" ranked weapons as well.
These are as follows:
Chapter 8: Requirements: Beat the chapter, and keep Lilliana alive. Weapon: Durandal, The Blazing Sword
Chapter 12: Requirements: Beat the Chapter in 20 turns or less. Weapon: Armads, The Lightning Axe
Chapter 14: Requirements: Beat the chapter in 25 turns or less, and keep Sophia alive. Weapon: Forblaze, The Infernal Element
Chapter 16: Requirements: Beat the chapter keeping Douglas alive. He is an enemy general, and will attack your units. Be careful, he can kill you and vice versa. Weapon: Aurelora, The Pinnical of Light
Chapter 20 A/B: Requirements: Beat the chapter in 25 turns, and keep Dayan/Yuno alive. Weapons: Miruge, The Bow of Winds/ Malte the Frozen Spear
Chapter 21: Requirements: Beat the chapter in 30 turns, bring Fa, and keep her alive. Also, have both Milady and Ziess talk to Gale, Murdock's DragonMaster leutenient. Weapon: Apocolypse, the Silencing Darkness
In the begining of the game you pick (put) your birthday in. Well the affin you get when you chose the month is useful when you use units. Whatever you affin is ex:magic then you do better with other units who have the magic affin.