How about a disabler missile? Only initially used by Authority vessels, they make their way onto the market. It will only work on unshielded ships, or those whose shields have failed, When it is fired it heads to the target vessel at speed, slowing down at the last moment so as not to destroy itself. When it connects it then puts a heavy drain onto the electrical system (which may well cause these systems to fail), while charging up its internal capacitor system. When this has a full charge the missile them dumps the charge back into the target vessel, overloading the electrical systems.