You could limit number of uses with a Resources based stress track. Call it Wealth or something.
Then, as far as effects go you could use enchanted-like items based off of Resources or a modified modular abilities.
I'd modify modular abilities by allowing you to change them as a free action, but you must take Wealth stress equal to the number of refresh changed. The new power only lasts for one exchange. You may extend two exchanges for each additional point of stress you take.
Wealth stress would cause social consequences if filled.
RE: Enchanted items: While Athletics at 6 is good, a grappling hook could be an aspect or collection of aspects which can be tagged either for a bonus or to allow movement in a direction usually not available. Or a movement roll allowing vertical movement. Auto-pilot could drive for you and free you up to do other things, etc.