If you've not found your answer yet; I can only speak for six months ago when I last tried to do this, but the rules at the time was that only swords made in the traditional manner with either folding or forging were legal to buy/sell/import/find if the blade is curved. If the blade (not including handle) is straight or less than 510mm (I think), then it's still legal.
So in summary, if the blade is straight or less than 510mm or forged or folded, then it will be fine to import. If it's not, then you won't be able to.