If you pre-order Final Fantasy XIII-2 from GameStop, you'll get an exclusive costume
for Serah. If you pre-order the game and you're a PowerUp Rewards member, you'll get her "Genji Bow" weapon as well. It's retroactive, so if you meet both of those conditions and pick up the game before February 2, the bow is yours.
There's no word on whether you'll be able to switch this weapon from bow to sword form in real time, or what magnitude of damage it will do to giant enemy crabs. Square Enix did, however, say it allows players to attack more frequently.