The prince of Yahweh's host said to Joshua, Put off your shoe from off your foot; for the place whereon you stand is holy. Joshua did so.
One could also cite God’s visit to Abraham at the oaks of Mamre (Genesis 18) and Jesus’ self-revelation to the two disciples on the way to Emmaus (Luke 24:13-35), though these were not life threatening encounters. Joshua would hardly have submitted as he did if he had not believed that this Man was the Angel of the Lord (cf. Exodus 3:5; Numbers 22:31).