2 Sam 20:10

20:10 the sword that was in Joab’s hand. It is unclear whether this is the sword that had fallen and so was retrieved, either from the ground or the folds of Joab’s tunic (v. 8 note), or a second weapon that had been concealed on Joab’s person (in which case the dropped sword was a decoy). At any rate, Joab is able to catch Amasa completely off guard and kill him, as he had killed Abner (3:27).