If you kill his first form in combat, you get to see his second form. He is like an end boss for Final Fantasy. The first time I saw that, after a year of playing, I thought it was a particularly neat way of revealing a more of Abysia's backstory.
Yeah, Ba'al is just a particularily badass Abysian and has always been. He's not a fake like Malphas!
I remember how they switched his first magic skill to something else... Astral/Fire I think, but I can't remember which replaced which. I just remember being a bit worried about it in a game back in the day.