A bracer (or arm-guard); is a strap or sheath, commonly made of leather, that covers the inside of an archer's arm to protect it while shooting. Bracers protect the inside of the archer's forearm against injury by the string of the bow or the fletching of the arrow. They also prevent loose clothing from catching the bow string. They normally cover part of the forearm only.
Then Ho-Hak took, from among the arrows on the mat, the leather bracer and fastened it about his left forearm, that the arm not be lacerated by the string, and took the small tab as well, putting the first and second fingers on his right hand through, that in drawing the string the flesh might not be cut to the bone.
Book 6, Raiders of Gor: Page 60