There is a possibility that I'm being misquoted/misremembered/misunderstood.
I've been trying to point out that full casters' real power is not the damage they can do or the foes they can trap with a well place control spells. It's the impact they can have on the story, the plot, the world. The evil warlord resides on a fortress on top of a cliff? Fine we'll fly to the top (or something similar), thus bypassing several encounters and traps and fighting the big boss fresh. And this is a petty, facile example. It can be a lot more profound than that.
This is something that needs a lot of thought and care. But it would be cool if martials had supernatural "martiallish" powers that could also impact the plot, perhaps in different ways. But I do agree that this should be limited - they aren't wizards, after all.
But perhaps things like diverting a river, or causing a great heard of buffalos to stampede over an enemy army ... that could be interesting no?