Regarding finish wear...Wear from what? Unless you're wearing kydex or leather britches, I doubt your clothes will provide coarse enough friction to wear a stainless steel gun. If your Defender is blued, you need to worry more about rust than finish wear as blueing is more susceptible to corrosion in a high sweat environment. Even a leather holster won't wear a stainless slide that much. That's why stainless is a good thing IMHO.
All that being said, Renaissance Wax would probably be your best bet for preserving the gun without ruining your clothes. Lube is a whole other story. I would suggest some sort of grease such as Tetra Gun Grease that won't run