No one is sure whether or not there is a cap on the increase in quality gains as far as I am aware. So if you're really focused on weaving, just throw every last point into DEX. HP from VIT seems to cap out around 170 or so at Rank 50 on a DoW class. Whether or not that is a good judge for any other stat, like DEX > quality for a R50 crafter is up in the air.

But it's probably a good place to start.