Ishbi-benob - A corrupt reading. The whole passage should perhaps run thus: “And David waxed faint. So they halted in Gob (as in 2 Samuel 21:18-19). And there was a man (in Gob) which was of the sons of the giant, etc.”
Sons of the giant - The “giant” here 2 Samuel 21:18, 2 Samuel 21:20, 2 Samuel 21:22 is “ha-Raphah,” whence, the “Rephaim” Genesis 14:5; Deuteronomy 2:11. The sons of Ha-raphah, or Rephaim, are different from the “Nephilim,” or Giants Genesis 6:4; Numbers 13:33. The sons of Anak were not strictly Rephaim, but Nephilim.
Three hundred shekels of brass - About eight pounds. Goliath’s spear’s head weighed “six hundred shekels of iron.”