This pattern is based on a number of representations of saints (and ordinary people in icons) that diverge from the Byzantine standard. Instead of chitons, wraps and capes, the people are shown in coats cut with a short front and a longer back, and long sleeves that reach down almost to the hem.
Judging from the iconographic representations, the coat was usually worn as a cloak, i.e. wrapped around the shoulders and fastened around the neck. However, Giliarovskaia’s comment is that it “could be worn as a cloak,” seems to imply that it could also be worn as a coat. According to later illustrations, the sleeves could be pushed up and gathered above the wrist, or sewn with slits in the upper part of the sleeve that served as opening for the arms.
Note that there the hemline is straight: this way, it will be longer in the back than the front.
As with other patterns, it is best to make a mock-up garment out of cheap fabric before transferring the measurements to good fabric. It may be necessary to adjust the overall length of the garment and of the sleeves. You may choose to redraw the pattern to the final length while keeping the width of the front suggested by Giliarovskaia, or simply to crop the excess fabric from the bottom (the width of the garment at the hem will be reduced).
The seam of the sleeve should meet with the underarm seam of the body. Adjust the sleeve and the armhole to fit.
The sleeve shows two lines near the shoulder seam; they represent trim, not cutting or sewing lines.
For the rest, follow the directions for the Kievan Tunic (sewing order, matching seams, etc.).