Isaiah 7:4, Amos 4:11, Zechariah 3:2, denotes the burnt end of a stick (Heb. 'ud); in Judges 15:4, a lamp or torch, a flambeau (Heb. lappid); in Proverbs 26:18 (Compare Ephesians 6:16), burning darts or arrows (Heb. zikkim).
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain, copy freely.
Easton, Matthew George. "Entry for 'Firebrand'". "Easton's Bible Dictionary".