I really don't have a clue who this guy was portraying but he looked like Falstaff to me. Jovial and robust he drew a crowd as he explained the latest in medieval weapons!
Falstaff was a Shakespearean character who showed up in three of William Shakespeare's plays. He was a fun loving guy I've read. Also Falstaff beer used a character that resembled this fellow in some of their early advertisements. So, being all the players and actors in the fair resembled renaissance characters with no names, I took the liberty to call this finely dressed gent, Falstaff!