Stopping them from using it is half of the issue. They will waste many attack rounds doing so over and over and over again if I just replace the scroll in their inventory. And as I have said, I have cracked the solution already using some old oblivion moding slight of hand.

I just wish Bethesda had allowed skyrim combat moding to be as flexible and powerful as the magic moding can be. More accessibility to the combat AI would help a lot.
If you're just worried about wasting it, why not just script the effect to add another if the conditions are wrong? It wouldn't solve them using it, but at least it would stop them just vanishing when used...