I'm certainly not qualified to answer this question. That's probably why this topic has not received replies, speaking theologically about the Holy Spirit is scary, as we would certainly not want to accidentally blaspheme the Holy Spirit!
While I can't say much, I think this discussion of essence vs energy is over thinking. Didn't this debate come up much later than the writing of the Creed? Isn't this distinction foreign to Oriental Orthodoxy?
For general information, there is: http://www.stmaryscopticorthodox.ca/content/articles/sermons/holyspirit.pdf
, and of course St. Basil's book "On the Holy Spirit".
The Liturgy of St. Cyril has:
"And send down from Thine holy highest, and from Thy prepared mansion, and from Thy boundless bosom, and from the throne of the kingdom of Thy glory, the Paraclete, Thine Holy Spirit, Who exists in a hypostasis; the Immutable, the Unchangeable, the Lord, the Giver of Life, Who spoke in the Law, the Prophets and the Apostles; Who is in every place and Who fills every place, yet no place can contain; Who, by His own glory, according to Thy goodwill, works sanctification upon those whom He loves, not as servants. Who is single in His nature, and manifold in His working, the fountain of Divine graces. Who is of One Essence with Thee, Who proceeds from Thee. The companion of the throne of the kingdom of Thy glory, together with Thine Only-Begotten Son our Lord, God, Saviour and King of us all Jesus Christ, upon us, we Thy servants, and upon these precious gifts which had been set forth before Thee... Upon this bread and this cup, that they may be sanctified and transferred."
I've always understood this line simply as the Spirit of God, which brooded over the face of creation in Gn 1:2, and which restores us and sanctifies us in the NT...