I suggested a long time ago that they should have a kind of repair kit system that could be used to repair any item and that's kind of what Dark Matter is but along with this I suggested that repairing an item using the correct mats should give you a chance to +1 the repair.

This would take durability to 125% and give you the stats of a +1 item until durability wore down to 100%. So if you got a +1 repair on a +3 item it would be like a +4 until it wore down. I would have preferred it had they done something like this.