OK, I thought up a little example that I think illustrates what I want (but I am probably wrong). I am using
Frank Castle (the Punisher) and
Lobo as to extremes of the broadly similar fictional martial antihero spectrum. Castle is supposed to be like a RL human and Lobo superhuman, but are otherwise very similar (aka the same class) in my example. The both fight hand to hand and with weapons, but no "magic" per se.
To me, and for this example, these characters are both the same class. I want the game rules to be able to support both characters. I want it to be able to play a full game as Frank Castle and to be able to fantasy that I can do things at the limits of RL skill and ability. I also want to be able to play Lobo and be able to punch a god in the face. I want both. I also want to be clear, from a rules perspective (but not necessarily in the setting / fiction) that Lobo's great strength is supernatural (and what that means). Why you ask? So that when my
player has his wizard
character cast dispel magic (or anti-magic) on Lobo he isn't confused why it doesn't work. Lobo is just that strong. My player needs a frame of reference to understand how magic works (and doesn't work) in the game rules.
I hope that is clear, but probably not. It is late and my dog woke me up to go to the bathroom so I am not my best self at the moment.