I personally think that Great Katanas look pretty nice.

Also, here is a list of the most common weapons for jobs. You can also find a weapon rating list at www.killingifrit.com.

WAR: Great Axe, Axe, Sword, and Great Sword
MNK: Hand to Hand
RDM: Sword and Staff
WHM: Club and Staff
BLM: Staff and sometimes Clubs and Daggers
THF: Daggers and Swords
PLD: Sword and Great Sword
DRK: Scythe, Great Sword, and Great Axe
SMN: Staffs and Clubs
RNG: Dagger, Axe, Crossbow, Bow, and Gun
DRG: Polearm
SAM: Great Katana and Polearm
NIN: Katana and Great Katana
BRD: Staffs, Clubs, and Daggers
BST: Axe, Sword, and Staff

Think I covered all the jobs. Hope that helps