nights sights are nice in a low light situation but learning how to point shoot properly can be just as effective. you're best tool in a lethal encounter is training. all the gadgets in the world don't mean shit if you don't know how to react. look around for some self defense courses in your area. even if you only take the NRA Basic Pistol* course it would still give you a leg up on most people.
*intended as a basic safety and technique course, not a defensive course