Job assignments for my folks are kinda simple:

Vaan = Assassinator = Masumune
Balthier = Destroyer = Ultima Blade or Fomalhaut
Fran = Executioner = Ragnarok or Sagittarius
Basch = Terminator = Excalibur
Ashe = Slayer = Save the queen or Holy Rod
Penelo = Eradicator = Stoneblade