Shields and Bucklers
A target was a small shield, or buckler, worn on the body. The original Hebrew words translated as "target" are (pronounced) key-don meaning something to strike with, as in a weapon with which to shield one's self and tsin-naw meaning a shield, used to refer to the Israelite version, but also with the alternate meaning of a weapon with which to shield one's self. Ironically, "target" has come to mean something to be fired upon, even though the original meaning referred to something that was intended to be impervious.
"For The Lord giveth wisdom ... He is a buckler to them that walk uprightly"
Goliath was very heavily body-armored, but he hit the ground, dead, wearing his physical armor because he came up against someone who was wearing the "armor" of God:
"Now the Philistines gathered together their armies to battle, and were gathered together at Shochoh, which belongeth to Judah, and pitched between Shochoh and Azekah, in Ephesdammim. And Saul and the men of Israel were gathered together, and pitched by the valley of Elah, and set the battle in array against the Philistines. And the Philistines stood on a mountain on the one side, and Israel stood on a mountain on the other side: and there was a valley between them."
"And there went out a champion out of the camp of the Philistines, named Goliath, of Gath, whose height was six cubits and a span. And he had an helmet of brass upon his head, and he was armed with a coat of mail; and the weight of the coat was five thousand shekels of brass. And he had greaves of brass upon his legs, and a target of brass between his shoulders. And the staff of his spear was like a weaver's beam; and his spear's head weighed six hundred shekels of iron: and one bearing a shield went before him." (1 Samuel 17:1-7 KJV)
The Lord is a shield, a buckler, to His people:
"As for God, His way is perfect; the word of The Lord is tried: He is a buckler to all them that trust in Him." (2 Samuel 22:31 KJV)
"The Lord is my rock, and my fortress, and my deliverer; my God, my strength, in whom I will trust; my buckler, and the horn of my salvation, and my high tower." (Psalm 18:2 KJV)
"For The Lord giveth wisdom: out of His mouth cometh knowledge and understanding. He layeth up sound wisdom for the righteous: He is a buckler to them that walk uprightly." (Proverbs 2:6 KJV)
Fact Finder: What sort of "armor" should Believers wear?
Ironically, it's that Christian "shield" that makes Christians a "target" of Satan.