John records that the dragon swept down a third.
That number indicates both his great influence (for he was able to sweep that many from heaven) and at the same time it indicates his limitation (for he was able to sweep only a third, not a half or more). It also means that the remaining hosts of heaven are greater than the armies of the devil.
4 His tail swept down a third of the stars of heaven and cast them to the earth. And the dragon stood before the woman who was about to give birth, so that when she bore her child he might devour it.