A weapon.
Absalom is caught in an oak tree and killed by Joab with javelins
Absalom rode on his mule and met the servants of David, but his hair caught in the thick branches of a great oak. He was suspended between heaven and earth, while the mule went on. A man reported the sight to Joab who took three javelins and thrust them into the heart of Absalom and had his ten armor-bearers surround, strike, and kill him. (2 Samuel 18:9-15)