Warning! This weapon runs on the assumptions that all forms of pony have inate magic, not just unicorns
>Electricity rail-rod:basically a thin conductive rod would be strapped to a pegasus' wing and they'd stick the tip of their wing into the cloud and draw all of the static electricity from the cloud. They would them just aim and use a spark of inate magic (the magical difference in their hooves that determines whether or not a cloud they kick will bust, expel electricity, ect.) to fire it.