What's the name of this ability / which FF is it from?

I am pretty sure that at least one Final Fantasy game has an ability that lets you give an enemy a random weakness - for example you can make an enemy weak against cold, or water. Probably as a Blue Mage ability, whether it was called that or not. What I'm trying to remember is the name of it, and (less important but it's bugging me too) which game it appears in. Can anyone help?

[Sasquatch]

In FFVI, Edgar has a tool called the Debilitator that gives its target a random weakness. I don't know if that's the one you're referring to, but that's probably the first time in the series that anything like that popped up.