'Leather' in the Bible

"Moreover, you also know what Joab the son of Zeruiah did to me when he dealt with the two commanders of the armies of Israel, to Abner son of Ner and to Amasa son of Jether, and he murdered them and put the blood of war in [a time of] peace. He put the blood of war on the leather belt that was on his waist and on the sandals which were on his feet.