It seems you want something not covered by the book, except for the open to imagination "unique enchantments" section. And unique also means priceless and very much unavailable, so its probably nothing a starting player could get hands on.
I read about one example in street magic, an enchanted katana that would automatically bind to anyone who wields it. Your pistols could be enchanted by a "increase pistol skill" spell, which should work similar to an "increase attribute" spell. Maybe quickened and modified to affect the wielder, so he would get 1 or 2 extra dice with those pistols...
Maybe if you have a nice GM, he would let you have a pair of pistols like that for 15 BP each...