Hmmm. So, what we are looking for is a late Norman looking figure but with bare legs and a round shield?
Seems like the best way to replicate it is to find a late Norman/First Crusade type figure with tight trousers and a separate shield. The legs can be made to look bare with minimal work and/or a paintjob. Packs of round shields are easy to find and can supply a replacement for the kite that will come with the figure.