The most effective way of defeating this Boss is to use Recoil Rod + Hyper jab (the Ex skill from Deathtantz Mantisk). Because your Hyper Jab destroys his missiles/torpedoes, all you have to do just charge straight up to him and press Jab repeatedly. He may sometimes leap away or fire the arrow beam. This does not matter because it is well worth it. If you have the Fire Armor, put it on and it will be an even swifter victory.