Cheap solution to unscrew and screw back a refillable lighter valve (to clean a lighter)
Go to basement, garage sale, or thrift store and pick up an old, regular screwdriver about the right size to fit the slot in the lighter.
Use a file, hacksaw, angle grinder or mototool type device to cut a slot in the screwdriver. Make the slot big enough to fit around the gas nipple.
Unscrew as needed.