I think Athene's is overtuned
When I play most of the healy/shieldy supports I feel like so much of my power is actually coming from 
Out of all the support items I think this is the one that is stealth OP. I think I get more additional healing power from it than
combined. The other stats on it are just the cherry on top, especially the magic resist which is one of the few ways to reasonably get some early in the game.
