Armour-bearers were aides chosen by kings and high-ranking military commanders for their bravery (they were at least as brave as those they served) and loyalty. As their name indicates, they did bear armour, but they were usually much more - roughly equivalent to modern-day adjutants or aides-de-camp. One of the most famous armour-bearers of Bible History was the young David who entered the service of Saul as the king's armour-bearer - because he was also very good at playing the Lyre.
The future King David began as the lyre-playing armour-bearer for King Saul:
"So Saul said to his servants, "Provide for me a man who can play well, and bring him to me."
"One of the young men answered, "Behold, I have seen a son of Jesse the Bethlehemite, who is skilful in playing, a man of valor, a man of war, prudent in speech, and a man of good presence; and The Lord is with him."
"Therefore Saul sent messengers to Jesse, and said, "Send me David your son, who is with the sheep." And Jesse took an ass laden with bread, and a skin of wine and a kid, and sent them by David his son to Saul."
"And David came to Saul, and entered his service. And Saul loved him greatly, and he became his armor-bearer. And Saul sent to Jesse, saying, "Let David remain in my service, for he has found favor in my sight." (1 Samuel 16:17-22 RSV)
Not long after, David faced the giant Philistine warrior Goliath on the battlefield - or rather, David alone faced Goliath and his armour-bearer:
"Then he took his staff in his hand, and chose five smooth stones from the brook, and put them in his shepherd's bag or wallet; his sling was in his hand, and he drew near to the Philistine. And the Philistine came on and drew near to David, with his shield-bearer in front of him." (1 Samuel 17:40-41 RSV)
To illustrate that armor-bearers were at least as brave and skillful as their commanders, Saul's son Jonathan and his armour-bearer alone successfully battled a much larger Philistine force:
"And his armor-bearer said to him, "Do all that your mind inclines to; behold, I am with you, as is your mind so is mine."
"Then said Jonathan, "Behold, we will cross over to the men, and we will show ourselves to them. If they say to us, 'Wait until we come to you,' then we will stand still in our place, and we will not go up to them. But if they say, 'Come up to us,' then we will go up; for The Lord has given them into our hand. And this shall be the sign to us."
"So both of them showed themselves to the garrison of the Philistines; and the Philistines said, "Look, Hebrews are coming out of the holes where they have hid themselves." And the men of the garrison hailed Jonathan and his armor-bearer, and said, "Come up to us, and we will show you a thing."
"And Jonathan said to his armor-bearer, "Come up after me; for The Lord has given them into the hand of Israel."
"Then Jonathan climbed up on his hands and feet, and his armor-bearer after him. And they fell before Jonathan, and his armor-bearer killed them after him; and that first slaughter, which Jonathan and his armor-bearer made, was of about twenty men within as it were half a furrow's length in an acre of land." (1 Samuel 14:7-14 RSV)
A later armour-bearer of Saul did not fare as well; he died with the king:
"And the Philistines overtook Saul and his sons; and the Philistines slew Jonathan and Abinadab and Malchishua, the sons of Saul. The battle pressed hard upon Saul, and the archers found him; and he was badly wounded by the archers."
"Then Saul said to his armor-bearer, "Draw your sword, and thrust me through with it, lest these uncircumcised come and thrust me through, and make sport of me."
"But his armor-bearer would not; for he feared greatly. Therefore Saul took his own sword, and fell upon it. And when his armor-bearer saw that Saul was dead, he also fell upon his sword, and died with him. Thus Saul died, and his three sons, and his armor-bearer, and all his men, on the same day together." (1 Samuel 31:2-6 RSV)
Fact Finder: What sort of "armour" are Christians to wear?