It's probably because you're not supposed to get Omnislash on disc 1. I guess it's just there for the crazy mofos to get it if they really want to.
I can't really remember what my average levels are at any stage of the game
But I started playing the game again yesterday, at Chocobo Farm for first time now.. I'll probably try to get Omnislash on disc 1 again, but I'm not going to get that far today or even tomorrow I guess