its impossible
No its not impossible, it just actually requires you to play the game in every aspect.
If you go in thinking "Oh im gonna play a sword and board knight who does not use magic but just pure strength" your gonna fucking die. To be able to do expect you have to:
Spec correctly.
Pick the right major skills
Unlock the arcane university ASAP
Utilize every aspect of the game including spells, enchant stacking, and alchamy
Have knowlege of enemies and what their weaknesses are.
Expect in Oblivion is actually a game that requiers you to know your shit.
Master is also doable, but master is about munchkin building, IE Max resist, and or max invise bullshit.