Ugh, I never know what to do with these. Giving it to a tank makes sense. Giving it to a mage also makes sense.

I think when it comes down to it, I make everyone cripplingly overspecialised and buff their main stats. If my tank is doing their job my squishy wizards shouldn't be getting hit anyway!

In games where there isn't really a main tank like in Tales of Xillia (you don't even get a taunting move until like the very end!) I might buff my squishy character's defenses, though.