St. Michael the Archangel is most frequently identified as the angel who cast Satan out of heaven and is typically illustrated with a giant sword that is being plunged into a dragon.
While this is one of the more popular images of St. Michael, Christians throughout the ages have also depicted St. Michael holding a pair of scales.
Why is that?
Guardian and receiver of souls
The Catholic Encyclopedia explains how St. Michael, "holds a pair of scales in which he weighs the souls of the departed."
This is likely due in part to a medieval text known as the Golden Legend, where it relates an encounter Mary had with an angel prior to her death, preparing her for her assumption.
Then behold, an angel stood before her amid a great light and greeted her reverently as the mother of his Lord. “Hail, blessed Mary!” he said, “receive the blessing of him who bestowed salvation on Jacob. See, Lady, I have brought you a palm branch from paradise, and you are to have it carried before your bier. Three days from now you will be assumed from the body, because your Son is waiting for you, his venerable mother.”
The angel’s name is not immediately revealed, but later on when Mary “died,” Jesus comes into the narrative and gives instructions to the holy archangel.
Christ nodded his consent and immediately Michael the archangel came forward and presented Mary’s soul before the Lord. Then the Savior spoke and said: “Arise, my dear one, my dove, tabernacle of glory, vessel of life, heavenly temple! As you never knew the stain of sin through carnal intercourse, so you shall never suffer dissolution of the flesh in the tomb.”
This and other legends may have influenced the liturgy, as prior to Vatican II St. Michael was mentioned in the commendatory prayer for the departed, "Let St. Michael the Archangel of God, Prince of the armies of Heaven, receive him and conduct him to the city of the Heavenly Jerusalem."
Furthermore, in the Mass for the Dead it says, "Let the standard bearer St. Michael bring them to that holy light."
There is no particular biblical basis for this role given to St. Michael, but the Church has embraced it and it continues to be featured in various sacred art that features the holy archangel.
