Usama ibn Munqidh
"An Arab-Syrian Gentleman and Warrior in the Period of the Crusades; Memoirs of Usāmah ibn-Munqidh "
A very informative autobiography about the time of Saladin and Lionheart from the hand of a well known islamic knight.
Some contents about his arms and armour and their usage. Very interesting and informative.
For example, the best syrian edged weapons (swords) in this period came from India. Many franconian and syrian Knights used two layers of franconian chainmail armour over eachother during the battle.
More details here:
https://en.wikipedia.org/wiki/Usama_ibn_Munqidh
I am thankful for further book tips.
Regards, Roland