Thf -> Nin Where?

[Nova_Dresden]

Thf + Gladiator -> Ninja
Thf + Arch -> Corsair

Thief will most likely be a job, not a class that evolves to a job. If anything I'd see something like a new class called Assassin or Rogue maybe that evolves to Thief and Ninja. The only complication in all of this is that the weapon defines the job. Daggers are currently Gladiator weapons, so Thief would require a new weapon or Dagger would need to be removed from Gladiator/Paladin.