You do realize Revelation is a vision given to John by Jesus Christ...a vision is symbolic, a representation...in the Scriptures spirit creatures are at times referred to as stars...
“When the morning stars joyfully cried out together, and all the sons of God began shouting in applause.” Job 38:7
They are fittingly referred to as stars, for they reside in the spiritual heavens, just as literal stars are in the literal heavens or sky...Revelation 12:4 refers to those spirit creatures who became demons by reason of their deflection, which was caused by Satan...the fall of these stars refers to their loss of the ability to shine anymore...
As for one third, it appears to be a symbolic way of stating that a considerable number were involved, and yet less than half, and therefore definitely a minority...in Revelation the expression “third” occurs repeatedly, in relation to the earth, the trees, the sea, the boats and creatures in the sea, the waters, the sun, the moon, the stars, the day and the men...Revelation 8:7-12; 9:15