Able to mask out the eye but the glowing part of it I use a plane on a different render layer to mask out the character.  The result comes out quite nice:


EXCEPT for the mask for the eye glowing effect (I duplicate the eye mesh to a different object on a different layer in order to have only the eye glowing, not with the armor (got a glossy shader) glowing too). As you can see, half the eye is still visible despite of I masked that out. It works for the glowing part, though:


Thanks for reading!

Here's come the blend. file:
In your node group change the way the matte is mixed with the glow. You want to add black to the matte in the shape of the plane:

Then add the result to the rest: