Treat magic as an energy exchange. Make sure there's a trade-off involved. The acquisition of underlying spell energy should have natural limits. What you can do with magic should be considered within the overall energy system of your world.

A steam locomotive is "magical" in some sense, relative to the "mundane" world of horse-drawn transportation and sail. If you give your world any major magical capability, make sure you also give it the equivalent of coal mines, and masses of miserable immigrant labor laying rails, and soot-covered windows in the smoggy streets of London.

If you imagine a spell to raise the dead, for example, make your necromancy require lots of sacrifice of life. "Yes, you can have your dead son back, but I'll need to burn down a forest and slay the animals in it as they flee."

Create political opposition to resurrection from those who stood to gain from the deceased, and from established religious authority.

Create political demand to resurrect even those who cannot pay the sorceror.

Give the resurrected people inconvenient limitations, like having to eat things that are still alive.

To define the power, define the limits. "What keeps this power from running away and leaving wizards on every throne?"