Correct about using this for casting stoneskin instead of earth (and then idling in earth staff) but Phalanx formula is based solely off enhancing magic skill.
Hidden Effect
+10% increase to Water Element Magic Spells
-10% decrease to Fire Element Magic Spells
-2 Avatar Perpetuation Cost for Leviathan and Water Spirit
+2 Avatar Perpetuation Cost for Ifrit and Fire Spirit
@ Everdyne
I think Water Staff will be about or the same potency on Repose as with light staff, but if you use a HQ light staff vs HQ water staff... the HQ light will win by default because of the 15%.