I'm part of a Viking Re-enactment group, and they deal with this a lot - especially going to events from the UK to the US and vice versa. Usually they do as was suggested above - wrap the heck out of them in bubble wrap, surround it in cardboard (usually cannibalized boxes reshaped into a tube) and check it with extra insurance... labeled 'sporting equipment' as swordfighting is indeed a sport. They've never had any problems with this, and the extra insurance usually keeps them from being delayed or lost.