Abu Ishaaq RA says:
"A person once asked Baraa bin Aazib RA: "Was the face of Rasulullah SAW shining like a sword?" He replied: "No but like a full-moon with its roundness." "
In making a comparison with a sword, it may have meant that Rasulullah SAW had a long face. However the glitter of a sword has more whiteness (shimmering) than being luminous. For this reason Baraa bin Aazib RA gave the similarity of the full moon, and not that of a sword. All these similarities are approximate descriptions, otherwise even a thousand moons cannot give the brightness of Rasulullah SAW.