Not a new monograph but interesting nevertheless.
A. Nowakowski : Arms and Armour in the Medieval Teutonic Order's State in Prussia. (http://virtuabis.free.fr/Arms%20and%20Armour%20in%20the%20Medieval%20Teutonic%20Order%20s%20State%20in%20Pr.pdf)
Thanks - I've got this in hard copy but a pdf is always useful.
We had a bit of a discussion about this book in the currently reading thread back when I read it in 2022, starting here:
http://soa.org.uk/sm/index.php?topic=137.msg82762#msg82762