For what it's worth, I share noodles' sentiment of Blaze Spikes, Ice Spikes, Shock Spikes, and Aquaveil, Blink, and Stoneskin were parts of similar cycles of spells, generally available between levels 10-30 to Black Mages and White Mages. If one were to "complete the Spikes line," then I don't see any reason why the Aqua/Blink/Skin line shouldn't be "completed" in kind.