What other job uses a polearm? Samurai can, but I can't imagine samurai without a katana. Dark knight has precedent for using a sword, and it would make sense to make two-handed swords dark knight-exclusive, but can you then imagine red mage, being associated with thaumaturge (which makes sense) but only equipping staves? Archer could easily go along the lines of other interpretations of the hunter/ranger class throughout the RPG world by making it class-based, but what about pugilist? I can see them adding a new class (ronin, perhaps?) from which samurai and ninja would branch off from. Or perhaps something like a rogue class having ninja and thief. There are so many ways everything could possibly break down, but it looks like the job system doesn't mesh perfectly with a class system based on equipping a single weapon. I suppose they could continue to do what they've done for relics where jobs get job-specific weapons, and that would grant them significantly more free reign.
Long story short, I really, really want red mage.