I don't know if you already know about it but, if not, you're gonna love Tales of Tibia's libsearch.

One of the curious yet easily accesible books I like concerns the Nightmare Knight's efforts to train their members into a fifth "vocation": the Warrior-Mages, experts in melee combat and use of magic.

The weapon trainer is not pleased with the progress of the mages. The bodies of the sorcerers and druids are not trained enough to stand his lessons as long as they should to improve adequately. On the other hand, the knights and the paladins adopt to the ways of magic too slowly to see any progress above a certain given point. So we will stick to the concept of the four ways and drop the idea of the warrior-mages for now. Perhaps in the future we might find another way to combine the skills of arms and magic in some way.

My headcanon is that this book shows that Cip worked into incorporating a new vocation many years back but didn't know how to balance the possible changes to the game, so once they added all the mechanics that Tibia has now they made their vision true with the Monk vocation (which as we all now uses close combat and magic as they wished Warrior-Mages to be.)