שמואל א, פרק ט״ז, פסוק כ״א

David's arrival at the royal court marks a significant turning point in his life. As he stands before Saul, he immediately wins the king's deep affection, which leads to a rapid shift in his standing within the palace.

Because of this strong connection, David takes on an official role. The primary approach among commentators [רד״ק, מצודת דוד, ביאור שטיינזלץ] is that David is appointed as Saul's personal assistant. In this trusted position, his duty is to carry the king's weapons and armor.

However, a completely different perspective suggests that this development does not describe David as a servant to the king, but rather highlights his sudden rise to greatness. According to this view [מלבי״ם], David reaches such a high rank, similar to the most important ministers, that another person is actually appointed to serve as his own personal armor-bearer.