There are two holes for attachment and a notch to the left suggesting that this is a buckle plate.

This is an extremely rare illustration of a warrior bearing a kite shield as illustrated in the Bayeux tapestry. They are shown in the tapestry in use by both Anglo-Saxons and Normans, but in the main the Anglo-Saxons preferred round shields.

Published in Hammond, B., 2013. British Artefacts Volume 3 - Late Saxon, Late Viking & Norman, p.73, item 1.8.5-d; and also in a book on The Anglo-Saxon world (Higham, J. & Ryan, M.J. 2013).