And of course also Icehockey,Football and a lot more. The german law is bit more specific about it (the exact amount of Joule is 7.5) http://www.dsb.de/media/PDF/Recht/Waffenrecht/Verwaltungsvor... e.g. the weapon/weaponlikethingy must have a muzzle. Also the Intention of usage is considered, so if you produce a hammer with the sole purpose to throw it at me, if may offend German law.