Some friends of mine who regularly use swords and armour for historical study and re-enactment use a type of wax on their metal objects to prevent corrosion. It doesn't provide lubrication, but they really aren't looking to make their swords, shields, bucklers, rapiers, etc. slippery in their hands either.
As to humidity control, I use a Remington dehumidifer for my gun safe and it works quite well - it costs $25, but has an enclosed gel pac and built in heating element in a simple plastic case. The gel pack is good for 5 years or more - simply put the unit in your closed cabinet/toolbox and it will abosrb up to 6oz of moisture. When the color indicator goes from blue to bright pink, just take it out and plug it into your AC receptable for 8 hours - it will warm up and dry out the gel and be good as new again - simply put back in the cabinet again. Repeat. Mine seems to do a pretty good job in my gun safe, which holds about 12 guns and is in a slightly humid basement.