Or you go a completely different route and engrave some of your spells in stone a.k.a. you buy them as a power, which costs the most, but it is going to make them most effective. Breath weapon for fireball spells for example. They are only weapon:2, but they don't cost any mental stress either. You could even argue, that it would be reasonable to only make it a -1 power if you already have evocation.
You could probably make the argument that it should be a -1 power anyway.