This is getting ridiculous. I can't get my head around how they don't follow on from the policy points. This is definitely the ignorance and plain right stupidity of one individual. I do feel as if you are being bullied, as many others have imported without any issue and providing token cards as proof of membership.
I would come to conclude that whoever received your documents didn't bother to read them properly at all.
I would definitely go to your local MP, if that helps at all.
The sword law is soo ridiculous that having a curved sword for religious purposes is perfectly fine, and can even be carried in public. The sword law in the UK is specifically banning samurai swords of the cheap fake type, even though you can get a curved stainless steel sword over 50 cm if it's indian or Persian.
To be fair there's no outcry from Japanese sword owners or community for them to change it. Unlike other communities such as the Sikhs, who can carry curved swords for religious purposes, and would have a voice.
Regards