Nonhumans

Yes, mage multi-classers can wear armor. Unfortunately, nope, you can't 'abandon' a class if you multiclass. Tut, what you're doing is called 'dual-classing', and is only available to humans.

Actually I kind of hate the demi-human vs human thing in 1E. Nonhumans are great at 1st level (look at Drow females for the worst example), but then have level caps and elves can't be raised. It's just a dumb way to try to balance things out... make one group great at low level and bad at high level, and another group just the opposite.

In fact, the whole elf +1 to hit w/ swords and bows, 90% immune to sleep/charm is really awful. Elf thief is sort of the way to go in 1E: no level caps and the +1 dex and skill bonuses are sweet.

And elves are immune to ghoul paralysis (but not other forms of holding/paralyzation/stunning).