Blue Eyes?

What's the significance of the blue-eyed girl in the margin to the left? Why blue eyes?

It's a plot device I'm toying with. I decided I needed a way to easily identify mages in the story and set them apart from the rest of humanity (other than the obvious, of course) and settled on blue eyes. Not just any blue, though. Eyes so blue they pierce your soul. Blue like looking into layers of glacial ice. The pale, cold blue you usually pay lots of money to get. Blue eyes that simply defy the laws of nature.

I know, it's a bit Frank Herbert, but it seems to be working so far. Oh, and in a further quirk, the color can be disguised from mundane sight by contact lenses, but mages always see through the disguise.