Interesting idea. Might actually work: with high repair skill, you could use more high-tier equipment. You could wield a flamberge in plate armor, but at the cost of WPF - this way, you have to be a good fighter yourself, stats won't do the fighting for you.
Alt solution, if repair skill sounds weird: Income skill. It doesn't effect repair cost, it effects the money earned per minute. The starting value could be 30 or something like that, and increased like WPF: you can get it up to a sensible level relatively fast, but it would become more and more difficult to reach higher income.
Definitely needs some balancing.