I don't think a complicated system with the gamer fighting instead of the character would work. I'm afraid it will be as in a Fifa game. You suck the first few days, get the hang of it after a week and after a month the highest difficulty setting won't even be a challenge.
You can dream about a perfect fighting system, but never will something like that be complicated enough after a while. And personally I get sick after repeating something like that over and over again (as playing matches in fifa when you are doing something like a season or career or whatever, or fighting every battle in (Rome) Total war). 'Get on with it, get back to the game'.
With magic it is easier, than you really can make a strategy (if there enough different spells available). To resemble something like that in the fighting system, you would need different moves that have different effects. But, to be honest, I can't picture something like that in my mind very well.
Thats why I suggested a combination of Gothic 3 and Guild Wars.
In Guild Wars there are skills to be used in the same way you would use a spell.
Thus thinking about wich skills/spells to use would become a very strategic decision. And as the combat system would become more complex so would the magic system.
If you wouldn't like complex fights it could be easily solved with a more complex difficulty setting.
So putting the fights on "easy" just would mean they would become less complex or require less hand eye coordination or reflexes.
but there would be more settings to put on easy or hard as you please.
for example I don't want a compass that points to where I should go. If it pointed to the North I would be happy. This might not be the case for other people so they would put this on easy.
This is just an example offcourse