Accordingly, the scribes and Pharisees
…threw down the just man… [and] began to stone him: for he was not killed by the fall; but he turned, and kneeled down, and said: "I beseech Thee, Lord God our Father, forgive them; for they know not what they do.
And, while they were thus stoning him to death, one of the priests, the sons of Rechab , the son of Rechabim, to whom testimony is borne by Jeremiah the prophet, began to cry aloud, saying: "Cease, what do ye? The just man is praying for us." But one among them, one of the fullers, took the staff with which he was accustomed to wring out the garments he dyed, and hurled it at the head of the just man.
And so he suffered martyrdom; and they buried him on the spot, and the pillar erected to his memory still remains, close by the temple. This man was a true witness to both Jews and Greeks that Jesus is the Christ.
—Fragments from the Acts of the Church; Concerning the Martyrdom of James, the Brother of the Lord, from Book 5
Hope this helps it was a staff or tool used by a dye maker of that time.