So good for RDM/NIN soloing as it lets you get off ichi even while being hit. I think it depends on the level of the mob compared to yours. Aquaveil saves you from an interrupt and has a chance of wearing off with each potential interrupt, similar to Third Eye+Seigen. Stronger mobs will strip Aquaveil in 1-2 hits while weaker mobs will take multiple similar to Third eye as well.