Ozma has Curse not Bad Breath. Bad Breath isn't that bad in Final Fantasy IX. Saber must have only fought him once. I remember beating it on my third try, but repeat battles were tough and based on luck. It all depends if he wants to hit you with the Curse/Meteor combo repeatedly. Doesn't matter what level you're on or what equipment you have. There is no defense against that. There's also no ability in the game that prevents virus so if you want to get rid of it, but I don't remember him even inflicting it, you'd have to use Vaccines.

But what's the point of stealing from Ozma? He's the hardest boss in the game, so you wouldn't really be able to put that stuff to use and from what I remember you can get that stuff easier from other places in the game.