Sounds like you're looking for a refillable butane pocket torch. I've got one made by Blazer that I've had for a good ten years with no problems. It burns very hot and has a little switch that locks it open.
It also does wonders on frozen car door locks.
They are available in many sizes and price ranges. Check cigar websites for them.


Edit to add: http://blazerproducts.com/lighters/