Tedronai: I think you're getting too hung up on being a rules lawyer in a system that's by it's nature meant to be flexible
In this case, the lesson learned is that, if something needs to happen story wise, you CAN handle it by coming up with a good mechanical reason, or you can just add an aspect to the scene instead and compel it. So, in this case, I could come up with an 11 shift magical block that someone has added to the combat from off screen - or I could just say that the block is an aspect that compels the player to do what the block was intended to do anyways. Either way, they will have to pay fp to overcome it (possibly several!) but in the compel scenario you hand wave the actual math and possibly grant the player a fatepoint as a reward for going along with it - or possibly more than one.
Either way, I'd give the players a basic idea of what happened (a magical shield) and they could roll lore to figure out more clues (there are spellcasters nearby!) The GM has narrative power to say how an aspect can be compelled, and even if you wish to up the Ante on a compel.
I think this is what people have been trying to tell me, I only really understood now. You just have to remember that aspects can be on anything, and as a GM, if there isn't one that fits your needs story wise, you can add them on the fly.