There were three types of arrows used by the military of New Testament times. 1. Plain arrows similar to arrows of today. 2. Arrows dipped into tar, set on fire, and shot. 3. Arrows that contained combustible fluids that burst into flames upon impact. Fire-bearing arrows were to inflict damage on fortified places. If an army had fortified its position so that the enemy could not easily break in to destroy it, then the enemy would revert to using the long deadly arrows of fire.
As Satan continually bombards Christian soldiers with the flaming missiles of temptation (to immorality, hatred, envy, anger, covetousness, pride, doubt, fear, despair, distrust), we must hold the shield of faith out front so it can completely protect us.
Above all, taking the shield of faith, wherewith ye shall be able to quench all the fiery darts of the wicked (Eph. 6:16)
(via Hillcrest bulletin)