The Swords are expensive if you are after real ones. If you have the cash make sure you can bring them back and make sure you declare it when u go back into customs. Bringing weapons on a plane is a big no no so do it all by the book.
As for places to visit make sure you have some downtime. There are so many things to see almost any place you go in Japan. I would say stick to Tokyo as a hub and go to other places for a few nights. I did Hiroshima, Kyoto Hakuba and Tokyo and over about 3 weeks.
The best place I went to was by far Fuji-Q Highland. It has some of the best roller coasters in the world. It is a bit tricky to get to but.. take a buss from Tokyo.
O stay in a capsule hotel .. just for one night its not the best but it is an experience lol