One thing I would like to point out, to keep in mind, Zeuq, is that the Glyph of Holy Light does "Double Dip". If Emerald Vigor applies the same aura increase that the Warsong does, then it would make sense for the shield glyph to do so as well...
But why would anyone care?
Even if it does affect shields, the only damage that's the problem is the DPS not controlling the fight properly (wrong target priorities), or the DoT from the Dream/Nightmare on heroic... And of course, things punching tanks face in (go go debuff stacking!). But really, going in there to buff your shields? You might as well stay out and not even waste your time.