[@Ellri] I think you are underestimating mudane soldiers a bit. For a start there will always be hundreds of mundane soldiers to ever one mage. Meaning that in the unlikely event that an army of mages and a army of mudanes were to battle, there would be thousands of mundanes for only a hundred or so mages.

Although the mages would successfully defeat hundreds in the mundane army (providing the mundane army has no mages what so ever) ultimately they would be overwhelmed by the mundane forces.

Mages are most effective when fighting alongside the main mundane forces and by doing this can help change the tide of a battle. This is why mages tend to be divided into small grouped throughout the army rather than being in one group; if the enemy were to target them with perhaps a volley of arrows or a cavalry then the army would be without mages and would put them at a distinct disadvantage (considering that not only would they have lost all their mages but they would now have no way to defend against the enemy mages).