Aptitude test. This won't be the only time we do it. There will be many more times. Especially during the first year in the academy.
We were told to find the way of fighting that we will be best at. If you're a warrior, it also teaches you to find the right weapon that suits you. If you're a magician, it will teach you which magic among all the magic you have learned you should use during battle and also to find the opponent's weakness. Finding out which magic will give the best result.
With how there are only a few magic that can be learned when you just awakened, I don't think there are many ways the magicians can fight. Unless they have a master who teaches them. Or maybe one way or another, they learned an advanced magic.