testing rwc rings vs sapphire wrist without the full setup, is not really fair for the ring though, because %atk of rwc ring affects weapon atk and equip atk (such as pyro, porcelio, physical set).
without main weapons and other flat atk+ rwc ring surely lost vs sapphire, as the 1 sapphire gives 100matk.
but 2 perfect RWC ring 6%atk +3int/str win by very little margin vs 2 sapphire wrist.
with or without pyroclastic the result doesn't change much.
in conclusion not worth to get the perfect enchant for gens.