Passage
If he be able to fight with me, and kill me, we will be servants to you: but if I prevail against him, and kill him, you shall be servants, and shall serve us.
1 Samuel 17:9 (DRB)
Nearby Context
1 Samuel 17:7 And the staff of his spear was like a weaver's beam, and the head of his spear weighed six hundred sicles of iron: and his armourbearer went before him.
1 Samuel 17:8 And standing, he cried out to the bands of Israel, and said to them: Why are you come out prepared to fight? am not I a Philistine, and you the servants of Saul? Choose out a man of you, and let him come down and fight hand to hand.
1 Samuel 17:9 If he be able to fight with me, and kill me, we will be servants to you: but if I prevail against him, and kill him, you shall be servants, and shall serve us.
1 Samuel 17:10 And the Philistine said: I have defied the bands of Israel this day: give me a man, and let him fight with me hand to hand.
1 Samuel 17:11 And Saul and all the Israelites hearing these words of the Philistine, were dismayed, and greatly afraid.
Study Lenses
The verse centers on "able", "fight", "kill", "servants", "prevail", "against", and "shall". It is saying that the verse draws attention to "able" and "fight", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 8's "And standing he cried out to the..." into verse 10's "And the Philistine said I have defied...", so "able" and "fight" belong inside that flow. In 1 Samuel context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "able" and "fight" with trust shaped by these words, not by a vague optimism outside the passage.