Do you mean with the helms and scrolls all over them? The shields are displayed in heraldic form. The helms display the crest as it would appear in parade or possibly tournament. The shields, without all the scrolls, vines and whatnot, display the registered arms of the bearer.
Appologies. I thought you were referring to a different book. The "Hewing or Dueling" shields appear in this manual as well as one by Hans Talhoffer. Here's some sparing with them on You Tube.
They were used for judicial duels and other such trial by combat.
Talhoffer's books cover several forms of Judicial Duels. There's even ways that they "Leveled the playing field" when the trial was between a man and a woman.
The man would be fighting while in a hole armed with a club or mace and the woman would be armed with "A rock wrapped in a veil".
Hi there! I had understood that these are Bavarian court garments. Terrific inspiration, and with some clear examples in other parts of the German speaking areas. But there are a few items that I haven't seen anywhere on a landsknecht image (like the low, slouchy ankle-boots: http://mdz10.bib-bvb.de/~db/0001/bsb00016900/images/index.html?seite=7). I also don't recall having seen the fringe that is present on the Waffenrock sleeves and neckline as on the bottom images of that same page, or the 'cowls' that over the neck and heads - other than in the Paumgartner Altar on St. Eustace: http://www.wga.hu/art/d/durer/1/03/3paumg.jpg .