If you preorder the game at GameStop you will receive a SOLDIER 1st class uniform as well as the Buster Sword. Although this isn't the only fan service outfit that the game will include, this one is a preorder bonus only, and it may just be enough to get some fans to do so.
Along with the announcement, Square-Enix has also released a mini trailer of sorts to show it off as well. The trailer shows it being used both in battle and outside of battle, and it also shows off some of the unique animations Lightning will get while using it as well.