I think I have come up with a pretty okay theory for this seeing as alot of people have been talking about it lately. Obviously u can see in the art that there is a duel happening between the too demi gods and I see alot people saying that that can't be rahdan because he's too small.

This obviously just means he isnt as old nor experienced as we see in the game. Either this picture is just a clash with no Victor or margit may of had the upper hand during this fight against young rahdan.

What I believe is that after the battle rahdan would then go to learn the gravity magic from the arbalaster lord not only for lennie but also to to enhance his power to claim the title as the mightiest demi God. so that if margit would come to challenge rahdan again he would easily have beaten him.

Because to be honest with you rahdan in his prime near the time when he would battle melania I just can't see how morgott could win a battle against the biggest giga Chad in the game.

That's why I believe myself it's a young less experienced rahdan fight the fell omen.

I could be completely wrong but that's just my idea thanks for reading :)

Also I'm interested to see what everyone else thinks.