I have a friend/Student who has been training in Japan for a while now and is about to leave. He would like to buy a Iaito from his teacher in Japan and I was wondering if anyone knew if its easy to just bring back if its declared or are there issues and costs?
https://www.gov.uk/import-controls-on-offensive-weapons In short, he can probably bring it back in, but he should check with Customs first, because the devil is in the details.
Be ready for customs checks on age of weapon - they have rules and regs about what comes out - even busted my balls on Fukuro Shinai til I gave them the death stare.
If it's boxed with "fragile" and "martial arts equipment" prominently displayed on the box, there shouldn't be a problem with it as checked luggage. Be prepared for a "magnet check" when checking in luggage in Japan as shinken have to be properly papered. Try and avoid using the word "sword" at customs. Instead say "aluminum iaito", and only elaborate if asked specifically. While it will be allowed regardless, it helps avoid hassles.
Check and double check with customs, then check again. Despite what the regs say I have known of a few people who have had trouble getting iaito into the country.