So according to description:
MaxHP, MaxSP +5%.
MATK +10, FLEE +10.
Variable casting time of Lord of Vermillion, Meteor Storm, Heavens Drive and Storm Gust is reduced by 1 second.
If the Upgrade Level is an even number, the cast cannot be interrupted and the variable casting time is increased by 20%.
If the Upgrade Level is an odd number, MDEF +1 and the variable casting time is reduced by 1% for every 2 refine level.
Is the odd number effect stackable? Or idk xD