Dark matter isn't that bad.

Just start working on maxing the sphere grid. You'll end up fighting those bosses in the monster arena so many times that the random drops add up like crazy.

I think I've customized two weapons with break damage limit like that. One with the ones you get from capturing, (I think it was on rikku's capture weapon. or yuna's. one of those, ironically) and another to make tidus' excalibur. (psh, who needs caladbolg, NOT ME!)