This is my favorite card in the deck, since it is one of the few that isn't "organized religion is bad, rawr."
Following Ciro's description of the Empress, Emperor, and Hermit, clothing color and background are the primary elements. He is dressed in orange, gold, and trimmed in purple; colors that are associated with royalty. Gold being wealth, orange being a type of gold, and purple being the most expensive color to dye (since it was made of sea snails.) Purple however is also the color of spiritually in occult settings and penance is actual Church liturgies. So while he is decked in royalty he has the burden of spirit and sacrifice. He just screams exudes royal priesthood. Another detail is that underneath it all, he has a white alb. So he has pure spirit and innocence at his core. The only other majors to share this are the Fool, Emperor, and Justice. (I don't include the High Priestess since it's a veil rather that cloth.) Also orange in this deck is the color of the Cups, which means emotions. Since this orange is draped with gold and purple I see them as good well tempered emotions. The Cups are the happiest suit and the pains of 3 and 5 aren't in vain since they can be sacrificial (purple). The patterns on his chasuble are vines and flowers, again showing the fruitful, beautiful, and goodness of his domain.
Again with the Empress and Emperor the background displays his domain. Here it is a stain glass window evoking a church, so royalty, sacrifice, and purity within the confines of religion. He is perfectly covered in it, so he is enmeshed in sacred time and scared space. He lives in kairos rather than cronos.
The Hierophant touches his crosier in the right hand. (I take the non hook shape as Ciro's artistic license such as the Wheel being a machine.) So he has authority to rule and guide but uses a light touch and is ready to grab it fully at any time. His left hand has three fingers out. If they were tighter it'd be a sign of blessing. It could be that he is counting and if so that implies he is saying his prayers. Devotions of multiple prayers show his dedication and love to his flock, since it requires a great commitment. (How times have you mediated, journeyed, brainstormed a card until you understood it?) He wears a Palium (that Y shaped collar with the gems) so he is either the Pope or a Metropolitan bishop, i.e. the bishop of the Emperor's capital, thus his flock is as big as the Emperor's kingdom. His hair is grey and he is bearded to show the wisdom of age. He looks down focused on his work but still walks, his vestments train and you can see his feet implying taking steps. (Notice how you don't see the feet of the Emperor even though his clothes train.) He may be weary but is job is big and eternal. (He will still work as Hierophant even after he dies. See Judgment.)
Finally he portrayed in profile which symbolize dignity, authority, obligation, and dedication. Usually this is reserved for a king's portrait or the Emperor card in the Tarot. However among the Majors the High Priestess, Lovers, Strength, Hanged Man, Temperance, and the World. are in profile while the Emperor is not.