The Virtue Angels are the fifth rank of Heavenly Spirits, according to Dionysius the Areopagite, a theologian of the 6th century.
He wrote that they preside over the elements of the world and watch over the nature. This is in line with the Catholic Church, who refers to these heavenly beings as the Spirits of Motion that govern nature, have control over seasons, the stars, the moon and the sun.
These Angels are in charge of miracles:
“And he came down with them, and stood in the plain, and the company of his disciples, and a great multitude of people out of all Judaea and Jerusalem, and from the sea coast of Tyre and Sidon, which came to hear him, and to be healed of their diseases; And they that were vexed with unclean spirits: and they were healed. And the whole multitude sought to touch him: for there went virtue out of him, and healed [them] all.” - Lu 6:17-19 AV
In the above mentioned verses you can see how the word virtue is being used to describe the healing powers of Jesus.
These angelic beings also provide courage, grace and valor. They also preside over the process of celestial life.
Angels are busy with two main activities: they assist or they worship. We know that all creatures must worship God, but the Angels have the privilege to worship God constantly and they get never tired of this!
You don't see the Virtues depicted that easily, but if you happen to see one, you see them carrying white lilies, sometimes red roses.
The red roses are the symbols of Christ's passion.
The Theologian Dionysius explains also that the Virtues, together with the Archangels and the Angels are in the third order of the Angelic Choir. They are also God's ministers who take care that the harmony of all things created by God remains untouched.