Sheena? Useless in battle? Yeah, okay...
I could never for the life of me figure out why everyone loves Kratos so much. "Oh, he's so badass and dreamy!" Not really, no. Regal is the real badass of the game. He kicks ass with his hands bound. Zelos also wins, because he's like a better version of Kratos in battle and a pimp.
I have to admit, it took me a while to fall for Zelos' charm. I found him annoying at first, but he really grew on me in the end. Although I haven't played it in a while, I don't remember many differences between his and Kratos' fighting ability, other than Kratos could cast Judgment.
So anyway, how the hell can you fit that much plot development into 80 minutes? You could get the "major" plot elements, but part of what makes the characters at least somewhat enjoyable is the development that happens outside of said major events.
Answer is, you don't. There's no possible way that they could fit everything into four episodes. I don't see why they didn't make it a longer series; I'd say at least twelve episodes. At least then you can fit in a lot more story and character development.