Who appeared to Joshua near Jericho with a drawn sword in His hand?

Answer: Commander of the LORD's army

Joshua asked, "Are You for us or for our enemies?" He answered, "Neither... I have now come as Commander of the LORD's army."

““Neither,” He replied. “I have now come as Commander of the LORD’s army.” Then Joshua fell facedown in reverence and asked Him, “What does my Lord have to say to His servant?””— Joshua 5:14 (BSB)