"Furthermore, the rate of increase for (dDamage/dPIE) seems to be lower than STR or ATK on higher ranked enemies."

"Piety may still have an important role when trying to land stuns from Leg Sweep and Heavy Thrust, but in terms of damage, Piety is the worst of the 3 major stats."

Isn't VIT the secondary stat for War like Piety is for Drg? Personally I've noticed Atk Power > Int on Mnk in terms of overall damage, but like most others I've yet to do a thorough test as well.