GLADIOUS ENDING

This is the best ending, just have to continue the game (whithout willing the Ice Fly) until you get to this location:

After this, in the conversation, when she ask you if there is something in Noelle's mind say YES, and pass the rest of text, after the text ends, talk with her again and when she tell you if Noelle is ready for help say YES, then after a more text you will go in a fight.

I put a red point in ACT's accion that you have to use, then spare the ice shadow.

After all this continue normally the game(without killing the Ice Spider), until you get to the battle VS Noelle:

This battle is really hard if you don't know who dodge her attacks, the only thing you have to do is attack Darkworld Noelle until she is almost dead, then the magic button will glow, then stop attacking and farm TP.

When you have 100% of TP use the movement we learn after the Ice Shadow fight, FORGIVE.

After all, we get the ending, only you have to visit Dess.

REVENGE ENDING

In this ending only you have to kill the Ice Fly or the Ice Spider:

After this, just visit Dess.

REBIRTH ENDING

The only thing you have to do is kill Noelle, you can attack normally or use a double atack in ACT with 25% of TP.

TIP: If you kill the Ice Shadow, you will learn mediatate, this is a ability in the magic menu that health you 12 HP for 50% of TP.

Then, only you have one thing to do. visit Dess.