I believe you will get the cap amount from gear based on your level. I do not think they have disabled the used of gear if its too high level above you.
IIRC: Using gear way above your level should result in you getting level*1.5 stats and clvl/5+1 skills while weapons (when hitting/casting) and armor (when getting hit) wearing off a lot faster. The closer the equip gets to your level the slower the durability loss.
Once you reach 70% durability you loose skills but keep stats from said piece of equipment. Necros e.g. only ever need to repair equipment with +skills as they themselfs basically never get hit while their pet getting hit results in a durability loss for your equipment.