Two German states are about to attempt introducing a law at the federal level banning all knives with blades longer then 6cm (~~1.5~2.3 in) from beeing carried in publicin public.
Source in german: https://www.swr.de/swraktuell/rheinland-pfalz/messer-verbot-gesetz-bundesrat-rlp-100.html
Seems like enough did: https://netzpolitik.org/2024/etappensieg-belgien-scheitert-mit-abstimmung-zur-chatkontrolle/