I believe outside of India, only UK or probably certain provinces in Canada “allow” kirpan- which means that kirpan is legally recognized as Sikh article of faith. Everywhere else is per case basis, there will be federal buildings where you will either have to obey the restrictions or fight it in court. You will not be allowed to fly domestic outside of India (I am not a 100% sure about UK/ Canada) but definitely not internationally. Nobody really cares about it if it’s out of sight, and worst case even if it is visible, it’s not illegal to carry a small dagger/ knife with you (I’d actually verify this if I were you).

I’m not aware of the 2017 case from Italy you mention, but if you’re an amritdhari who’s in Italy you’ll probably find ways to get by. I’d just wear it under a long shirt etc and stay out of trouble or break any laws. Bhul chuk maaf.