I was doing some research when I came upon an illustration from the Lives of two Offas, from the mid thirteenth century. The illustration depicts a fully maille armored knight, but he is wearing a solid plate defense on his face. It resembles the front of a great helm, but it is worn like a mask over the coif, covering only the face, not the top or sides of the head. Is anyone familiar with this?

This one.
http://www.bl.uk/onlinegallery/onlineex/illma...07000.html

Yeah, that's it

maybe it is a chain hood worn over a back of the helmet

No, from the detail in the picture it is clearly worn over the maille

Yes, other people are familiar with it.

1. Although the manuscript as a whole is dated to circa 1250, some of the miniatures including the one in question were added later and are dated by the British Library to c. 1320.

Quote:

The difference between Matthew's style and that of the 14th-century additions can be seen by comparing this drawing with the similar battle scene on f. 3v.

http://manuscriptminiatures.com/4089/12324/

2. As far as anyone has determined, this is a one-off illustration, with no other known examples showing this.

My personal opinion is that this shows a face mask laced to a mail coif with plate cervelliere beneath.

Could it be a mail coif worn over the greathelm?

From the illustration it is clear that is not the case

Thanks! I wanted to make a reproduction of it