[Exxy]

Just to make sure, Guard Break only gets applied if you use a GB effect on someone who is actually guarding, right?

I'm more-than certain it only gets applied if an opponent uses Guard (which is why Ran and Esther's comments confused the $@#% out of me).

And while we're on-topic, I don't imagine being able to use Guard while you're afflicted with Guard Break to work well. Maybe at half-effectiveness or some such (at the risk of them breaking your Guard again, to either power-up the effect/duration or to completely remove the option the to Guard after second go-around - more as a, "fool me once, shame on you; fool me twice and shame on me" type of thing), if it doesn't already flat-out restrict you from Guarding again while afflicted with the debuff.