I feel like Stamina has become a real catch-all stat. It affects some magic damage, it changes how much poison/regen ticks do, your chance to be hit by statuses, it's a kind of magic defense, and now for 1.9 it will apparently influence both cover and counter rates? That seems like a lot, especially when stats like Vigor are just physical damage and defense-kinda, and speed is just speed.
Should cover be determined by speed? After all, you have to get out in front of our ally, right? Counter maybe could be vigor (I could see why stamina also fits, though).