Flying Toaster
Explorer
Let's face it, the leveling up and training rules didn't make a lot of sense either. They were pretty crippling to the thief as well considering one of those could level up based on XP long before they had the money to do actually do so.
Strict application of the training rules would also act as a disincentive to exploration. It would be hard to go hex-crawling over the hills and far away, or sailing off into the wild blue yonder, if you know that you cannot level up until returning to a home base of some sort. Explorers would have to hope they can stumble across friendly high level NPCs willing and able to train, or else get stuck at current level for who knows how long.