Put helicopter tape type stuff on it when it's new, it's much more abrasion resistant than the metal itself.

Look at your cleat adjustment, make sure you're not pedalling in a very unnatural way. Some people just do it, I scuff my seatstays with my heals too.

move your feet out a bit on the pedals ?

dont worry about it, i always wear the arms on new and old xt cranks. if you use clipless pedals you could try spacing out your cleats but correct position is far more important than cosmetics

Shimano spd DX pedals and fairly tight. Abit too tight at times!
The crank arm is alot more bulbous than my old Saints that too ages to rub paint off let alone the arm itself

Polish them, then put heli tape over the polished area....the end

Perhaps you just pedal heels in, I knwo I do and I rub on my cranks a bit

fact of life.

if you walk duck toed, get used to it...it's just the way you were put together.

makes your bike lighter I heard