First of all, we have a well-dressed angel here. She appears to be wearing pretty much the whole armor of God as described in Ephesians 6. She has her waist girded with truth and a breastplate of righteousness, the helmet of salvation, and her feet are shod with the gospel of peace. If there are times when the angels in heaven might wear the armor of God, how much more do we as mere humans need to gird ourselves with this power from the Almighty?
"For we do not wrestle against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this age, against spiritual hosts of wickedness in the heavenly places" Ephesians 6:12.
I love that this angel is trampling on a demon who was up to no good as evidenced by the pitchfork in his hand. Paul says, "Put on the whole armor of God, that you may be able to stand against the wiles of the devil." This angels posture might also allude to the verse in Romans 16:20, "And the God of peace will crush Satan under your feet shortly."
Now to the set of scales that she prominently holds in her hand. These scales are used to weigh one thing against another thing. In this case, God would be weighing our righteousness against our unrighteousness. The angel even holds a blazing torch that symbolizes how nothing can be hidden from the light of truth. We know, of course, that our righteousness (or good deeds) can never outweigh our unrighteousness since we all have sinned and come short of the glory of God, and all our righteousness is as filthy rags before a holy God.
The classic verse relating this is found in Daniel 5:27 when the hand of God Himself wrote a message to King Balshazzar on the wall, saying, "You have been weighed in the balances, and found wanting."
That same pronouncement could be made over each person who depends on his or her own goodness to get them to heaven. We always fall short and will always be found wanting in our own selves. "It is by grace we are saved, through faith and that not of ourselves, it is the gift of God not of works, lest any man should boast." Once your "balance" is filled with the righteousness of Jesus Christ as Savior, you are no longer lacking. He fills your scale with Himself and you are forever made worthy through Christ.
Amazing Grace -- oh, how very sweet the sound!!