‘His appearance was as lightning, and his raiment white as snow, and for fear of him the watchers quaked, and became as dead men.'
The appearance of the angel was as lightning in its splendour, and his raiment was pure white. They would be reminded of Daniel's vision when he too had seen an angel fitting this description (Daniel 10:5-6). ‘White as snow' indicates a certain God-likeness (Daniel 7:9). So glorious was the figure that the guards at the tomb, ‘the watchers' (compare Matthew 27:36), themselves quaked (the word is used of the earthquake in Matthew 27:51) and swooned, becoming as dead men. Thus when the women approached there was nothing to fear, apart from the angel.
The description of the guards as ‘the watchers' is probably ironic. Men had set them to watch, and now they could watch no longer.