If you would like to provide certain services in other EU countries, you will need the EU certificate as proof of your professional experience for some EU countries (e.g. Austria, Belgium, Luxembourg).
If you want to temporarily take weapons or ammunition abroad from Germany, take them temporarily to Germany or take them through Germany, you need a permit.
If you have a training qualification from abroad, you can apply for official recognition of your training qualification from the Chambers of Industry and Commerce (IHK) in Germany.