To see the good ending, defeat the final Boss normally. To see the bad ending, defeat the final Boss with a map weapon (for example, Trey's Corey and Lyserg's Chloe).
Getting enough energy for Halo Blade
Make sure you have enough Furyoku in the bar. Also, your Furyoku in the circle must be in the red. Note: To make the ball go red, do a normal punch ( Square ) or keep on blocking there attacks. However, do not block too long or you will get KOed.
Secret Characters
Beat the game to get the 2 player versus mode unlocked. Then, press select on the following characters. Press select again to revert back to the original.
Code - Effect
Hit select on Matilda - Play as Marion Fauna
Hit select on Kanna - Play as Matilda
Hit select on Yoh Asakura - Play as Zeke Asakura
Hit select on Meril - Play as Masked Meril
Unlock Matia and Mari
Highlight Kanna and press SELECT. Press SELECT again to change to Mari.
Versus mode
Successfully complete all twenty episodes in story mode. The versus mode option will now be unlocked at the main menu. You can play as Vineuvail, Zerumo, Lyserg, Heckel, Tao Len, Faust VIII, Ruby, Kanna, Lee Pai Long, Trey, Zaua, Meril, Rio, and Yoh. You also get one random secret character, such as Silva or Zeke.
Yoh Halo Blade
You will learn this special move after you read the Tome Of The Shaman. Press L1 + R1, Up to execute it.
Zeke
After you beat the game go to verses mode and highlight Yoh Asakura and push select. His picture will be replaced with Zeke's picture. The upside to Zeke is that he has longer range and is stronger but it is easier to break his guard because he doesn't have a shield.
Alternate endings...