What does 1 Samuel 17:42 mean?

To say that Goliath was a confident man would be a massive understatement. When he went out alone into the field and approached the battle line of the Israelite soldiers, they fled (1 Samuel 17:24). He was an intimidating warrior of the fearsome Philistine army covered head-to-toe with the best armor and carrying with him enormous battle weapons (1 Samuel 17:4–7). He, and nearly everyone else, believed he was unbeatable in one-on-one combat (1 Samuel 17:8–11).

Now, after forty days (1 Samuel 17:16), a man has been sent from the ranks of the Israelites to respond to his challenge. But as David gets closer, Goliath realizes he is just a youth (1 Samuel 17:12–15, 33), apparently without armor (1 Samuel 17:39–40). The text mentions David's appearance (1 Samuel 16:12), perhaps suggesting from Goliath's perspective that David is merely a "pretty boy" and does not in any way have the appearance of a warrior. Goliath has no respect for this challenger.