Funny thing about the WS Merits is that you're more likely to use it for jobs that arn't your favorite because you lack a good weapon for that job. EX: My favorite job is NIN, but there's no reason for me to get Shun because Blade: Hi will outdo it in just about every situation factoring in AM. It would be more beneficial if I used my limited WS slots to instead upgrade my other jobs which I didn't bother spending an absurd amount of time 99-ing a REM weapon for.

Granted, I have Shun merited anyway because I'm NIN-crazy, but that's beside the point.