Yeah, nice story Indelacio.

I just wanted to say, the castle of ordeals isn't the key to class change, it's just a series of trials for dragons (or light warriors, in this case) to prove their bravery.

At the end, the item that they collect is proof of their bravery, and Bahamut then accepts them as true warriors, or something like that.

As well, the item changes form for whoever collects it, so while the light warriors got a rat's tail, other people would have got different items.

After Bahamut saw that the warriors had received the item of bravery, he bestowed upon them more worthy names of warriors, inducing the class change.

PS. One of the dragons hinted there used to be a time where dragons and humans lived in peace. Would this tie in with your Northern Civilisation ideas?