In my book I'm writing magic most certainly doesn't make you weaker in most cases. One character does, but there's a plot reason why. He's exerting and over extending himself beyond what his mind and body is really capable of doing.

The other mages in the book by contrast are quite physically fit. In particular a Barbarian from the north learns at the Academy and is frightful in battle using magic to enhance his already super human strength. Smashing the ground and causing a visible crater and scattering lesser men is well within his capabilities provided he uses magic.

Magic is limitless in so far as you can think and free your mind. The more you learn and the more you make use of magic and any ideas the more you can do. So someone who studies time will be quite an adept master of it, but your ordinary citizen might be capable of simple things like cleaning things easily, levitation, and getting the plow on a farm to move itself.

This nation of Mages has quite consistent catastrophes to mages losing control of their power. The latest being the lost northern city which was blown away. The notivitates were trying to impress their masters and the experiment got far out of hand leaving a blast behind much like that of a nuclear bomb. A constant storm of radiation and various magic permiates the area, and will for quite some time.

This country of mages is capable of producing special metals out of regular application of magic. Creating super dense metals and then with magical enchantment negating the weight of the blade except when it strikes on impact. Soldiers are supremely trained in mind, body, and spirit for war. Because of the countries large size and small population each and every guard is supremely capable. Being able to blink and vanish around the field of battle cutting a swathe of destruction through enemy soldiers is effortless. Unaided a single soldier can cut down scores of men unless they have some kind of magic.

Politically a country of mages is powerful, their low population and distance from the rest of the world matters little. They're the only country to perfect teleportation. First as warp gates and then next as a personal spell. Angering them is not a good thing because it could mean an elite hitman squad of death in minutes. They can project their power with ease.

Despite all of this they are only equals to the Western Empire which is stupendously vast and always expanding. They also have in the past captured and crucified mages torturing them to insanity and harnessing their power for themselves. While rare it's not unheard of to see one or two crucified insane mages being held up on a cross protecting the soldiers. The country itself looks down upon magic, and unlike the other country it's very rare for them to be capable of it. Those who do are often press ganged into work as healer, protectors, and armorers.

I could go on, but yeh. Just an example.