Saint Selaphiel, also known as the archangel Selaphiel, Selatiel, Saint Sealtiel, or Salathiel, is an angelic or celestial being found within the apocalyptic Second Book of Esdras. This book of scripture is noncanonical within Christianity, and thus the archangel Selaphiel is not always recognized by all denominations of the Christian church. Selaphiel is one of seven official archangels celebrated by the Eastern Orthodox Church, and the angel is also a part of folk traditions within Catholicism as well. The fact that Selaphiel is recognized within both the Eastern Orthodox and Catholic Church, means that the character Selaphiel was recognized as an archangel within Christianity before the East West Schism took place. Outside of the Eastern Orthodox and Catholic Church, there are many newer Christian denominations that do not recognize Selaphiel as one of the archangels, as he's not mentioned in either Old or New Testament scripture.
When shown in iconography or other early period works of art, Selaphiel is usually depicted as a character locked within humble prayer, with his eyes being downcast towards the ground, and his arms being crossed over his chest. This manner of display is universal regardless of Christian denomination. As the artistic depiction of Selaphiel suggests, he is the Saint of prayer within the Eastern Orthodox faith, and is responsible for helping Christians to pray. It is said that through his guidance, you will be able to pray to God without distractions, lack of focus, or inattentiveness. There are even special prayers that have been attributed to Selaphiel, which if practiced are thought to help bring a person to the point that they can become very focused and engrossed within prayer, a sort of warm of prayer if you will. This warm up prayer is prayed to Selaphiel himself, who upon receiving it will personally help the person praying to him.
The artwork that is available depicting Selaphiel is extremely beautiful, especially the Eastern Orthodox Christian iconography. In most of the paintings the archangel is shown wearing a flowing pastel pink outer robe, with a pastel purple colored inner robe visible near the angel's feet, and on his left arm from shoulder to wrist. The angel's wings are also out in full view, with the outer feathers colored with the same pastel pink as the outer robe, and with the inner feathers or wing base shown as a turquoise blue color. The angel's head is tiled slightly downward towards the clouds that he's standing upon, and his glaze is very humble looking. Behind the angel's flowing brown long hair, is a aureole or halo, which is embossed with gold colored paint. If you have a chance to review one of these paintings of Selaphiel, be sure not to pass it up, as it's well worth it viewing. The contemporary works are usually much nicer than the old era pieces.
As far as Catholic depictions of Selaphiel are concerned, they will seldom be referred to as Selaphiel, as Catholics usually refer to the archangel as Sealtiel. Despite the different name, both Sealtiel and Selaphiel are the same celestial being. The artworks depicting him are usually in the form of sculptures and statues, with some looking quite similar to the Eastern Orthodox iconography, while other look quite a bit different. In some cases I have seen Catholic depictions of the angel holding a sword and shield, and looking quite sinister. In other pieces he is shown holding two fish attached to a string, along with a staff and water gourd in his other hand. In very contemporary Catholic works the angel will sometimes appear as though he is ready to embark upon a new crusade, as he is wearing full body armor that one would expect to see on a medieval field of battle. I'm not sure why he has a new knightly appearance to him in recent works.