The phrase “the prince and kings of Persia” is in reference to fallen angels who have authority and great power. Their power is not in the sense of position but of physical power.
The moment you get saved by accepting Jesus Christ as your Lord and Savior, He gives you the helmet. The helmet protects you from a deadly force hitting your head, causing you to be unconscious.
The Roman soldier’s sandal had hobnails—short nails that had a thick head to improve durability on the battlefield and to keep the soldier from slipping.
Since we are fighting against spiritual forces of wickedness, we need to have on—our spiritual protection with its weapons—the full armor of God.
Our fight is not against people but against ideas, teachings, and interpretations that come through manipulated people, who have been deceived by way of demonic activities in their lives. False teachers are motivated by powerful spirits to preach doctrines of demons (1 Timothy 4:1-2).