Lord Tristan,
after reading your post about the moves you've made with your shield, oh man, you're going to love SCA tournaments. However, on a note of "safety" shield bashing, or for that matter anything offensive with a shield, is not really allowed on the tournament field. On melee battles, pretty much anything is fair. All I can see is someone who thinks the "wrap" is the end-all-be-all move getting handed in a melee by your shield techniques!
www.armourarchive.org (if it's okay to post a link to them) is a great group of die-hard SCAdians who strive to "get it right" within the sport of the SCA. Most SCAdians I've met have called them a bit "extreme" but that's part of the fun of it, SCA caters to a large variety of people's interests from Genericelt/vikings to people who go way in depth in their persona and garb down to a decade with only extant examples via museum and effigies.
Beyond that, the Codex Manesse source is EPIC! I've been primarily studying I:33 as that's the closest to what I'm trying to learn, crusades techniques with a kite or at the most advanced, a heater and transitional armor.
here's something else I've found. It's SCA based, and definitely tertiary although most of their references seem to be quite good:
http://www.threeriver.org/marshal/tourney_1.shtml pretty good starting point for anyone interested in 12th century, but beyond that, it's the illuminations they use that I wish I could find elsewhere...