Hi Megan: University Products or Gaylord are my usual suppliers. You may wish to consider buying blue board and make your own sword box. A tube or “square tube” as I liked to call it, used for map or rolled item storage,might be long enough; or cut one down to fit on another one using hot glue or since on the outside, good packing tape.
The belt should be stored separately. Gaylord has some 3 inch high boxes that might work well for the belt. I would pad the box with appropriate tissue / polyester (read Gaylord’s description of which tissue for animal products) and pad the belt so it does not get a pair of creases or cracks. Might want to put tissue or acid free paper between the buckle and the leather. Buckle might have a tendency to have some green oxidation where it meets the leather. Better to remove the buckle for storage.