‘ And so it was that when Joshua was by Jericho, he lifted up his eyes and looked, and, behold, there stood a man opposite him, with his sword drawn in his hand, and Joshua went to him, and said to him, “Are you for us, or for our adversaries?” '
Joshua was probably on a surveying expedition to look at the possibilities for attacking and capturing Jericho when he came across an armed man with sword drawn. So he challenged him whether he was a man of Israel or a Canaanite. Possibly he saw him as one who may have come out to challenge an Israelite champion to single combat as Goliath would later (1 Samuel 17:4).
“With his sword drawn in his hand.” This is central to the thought. Compare Numbers 22:23; Numbers 22:31 where it was the Angel of YHWH Himself Who stood with a drawn sword in His hand. Once he learned a little more about the man, this vision would probably spring to Joshua's mind. In Scripture the drawn sword is an instrument of impending judgment (1 Chronicles 21:16; Ezekiel 21:2-5; also Ezekiel 5:2; Ezekiel 5:12; Ezekiel 12:14; Isaiah 21:15;. This figure was therefore indicating that YHWH was about to bring His awful judgment on the Canaanites, as represented here by Jericho. YHWH Himself would fight against Jericho, but against Jericho as the first of every city in Canaan (compare 2 Samuel 24:16-17; 1 Chronicles 21:16). In the words of Ezekiel 21:9, ‘a sword, a sword, it is sharpened and also furbished. It is sharpened that it may make a slaughter, it is furbished that it may be as lightning.'