Custom stunts or house rules. And a build that is generally more focused on their one kind of magic.
Some custom stunts adding to making declarations for thaumaturgy (or about their magic for evocation), or letting them take an extra two consequences for thaumaturgy/evocation in their one area can give them a much higher power level than a wizard when it comes to just that.
You could also allow focus practitioners to take specializations. That would also help as well.
But some sample builds, at refresh 8.
Kinetomancer: Guy shoots blasts of force and such.
High Concept: Kinetomancer for Hire
Skills: Discipline 5, Conviction 5, Lore
Powers: Channeling (Spirit), Custom stunt for 2 extra mental consequences, refinement*4
Items: Staff: Offensive Control+5 Ring of Power: Offensive Power+2, Enchanted Item 7 shift block, 5 uses per session.
Other Notes: This guy will get compelled whenever he wants to create light, lay out fear on a group of vamps, or veil up. This provides fate points further powering his magic.
Summary: This can be further used to increase his magical ability. A wizard who tried to do something similar might be able to reach the same level of control, but his power would be less, and he would have two less shots.
Transformer:
High Concept: Robot in disguise Witch Lord
Powers and Stunts: Ritual: Transformation and Disruption. Custom Stunt=+2 for lore declarations for transformation/disruption. Custom Stunt for extra consequences for transformation and disruption*4=8 extra mild consequences,
Skills: Lore 5, Discipline 5
Items: Control+2 Complexity+2
Summary: She blows any wizard out of the water when transforming something. (Which includes oh so much of thaumaturgy.) She has 9 consequences to the wizards 1. She would be able to cast a 25 shift ritual basically every other scene. She could for example place half a dozen aspects on herself to prepare for combat. Or drop a weapon grades entropy curse on a pesky vampire. Or obliterate said vamps mind. The wizard OTOH manages at about 9 shift spells without declarations. Something she'll be better at as well.
Basically a focused practitioner can have an extra 5 refresh to spend on their abilities when compared to a wizard. It can allow them to be more competent in their one area.