I don't recall seeing anything like that in an Effigy...

Is this kind of what you are looking for? Just a historical reference to it?

http://i3.squidoocdn.com/resize/squidoo_images/-1/lens3421902_1237553106medival-helmet-01.jpg

Have you tried looking in http://effigiesandbrasses.com/?

I didn't see it right away under the 1220-1250 time period.

Good luck!