Just some general observations on the game.
The amount of experience for defeating monsters seems random. For example, for the last boss, the creator, I have been given as much as 240,000, and as low as low as 50,000 points. It doesn't seem to matter what level you are, or how much HP or SP you have at the end of the fight. There's just no rhyme or reason to it. Because of this problem, and yes it is a problem, since you can't determine how many levels you will get from the last boss, it's probably a good idea if you fight a low end monster to gain levels, starting at least 10 - 5 levels away from the level number for the medal (because you can easily gain more than 10 levels from the last boss fight). Also see the last part of this post for why saving a backup SOL file may not be reliable.
Out of all the attributes, Speed is the most worthless. Unless you want to swing the first blow, and can't approximate how much damage you take each round, then put points into it. Otherwise, your just wasting point with it, and you should put them in strength, or magic - depending on what class you want to focus on. I also find that putting points into Vitality, or willpower, seems wasteful too, considering your HP and SP go up automatically with each level you gain. Lastly, since speed doesn't amount to much in the game, choosing the Moonlight Axe would be a good idea, since it's the most powerful weapon in the game.
Saving seems a bit wonky in the game. Currently, it won't save for me past level 55 - something I discovered after the problem Fooliolo already pointed out with the level medals. So, relying on a backup SOL file may be a waste of your time. I think that beating the final Boss may have something to do with it...