It's definitely OK to bring them back, my husband and I brought 15 back in November (long story on why we needed that many swords, good thing we had a sturdy fencing bag we brought with us).

It was comical at the airport, when they asked us did we have anything to declare that may be considered a weapon we said yes and they sent us to another line (I reccommend not lying about this--with so many spot checks if you get caught it could mess up your day). They searched our luggage, which means first they x-ray, boy the alarm went off with our luggage, and then you empty the suitcase in front of them.

My husband started to empty the fencing bag. The sword maker had wrapped each sword, so sword shaped package after sword shape package kept being pulled out. My husband looked a little nervous with these guys with machine guns and dogs looking sternly his way, a small group of them gathered. When he turned his back, the guards looked at each other, broke into big grins, and simultaneously said, "TOLEDO" and laughed. We didn't have to unwrap the swords--just repacked and checked them in.

FYI, buy your sword in Toledo--they are the cheapest there. If your a serious sword collector (or living history re-enactor like my husband he does a lot of work for national parks and museums) there is only one place to go--the 7 fingered swordsmith of Toledo (can't remember his name, I think Zamora, my husband isn't here to ask), he's mentioned in Rick Steve's guide. We spent a day with him, the menfolk intensly discussing sword reproduction while the womenfolk got very bored and focused on the jewelry his brother makes.

Have fun and remember, check your pointy things with your luggage.