This Apellarib or Apellarip is probably the uncle of Gregory Magistros, of the famous family of Bahlavouni. They were active supporters of the Bagratids, the Armenian kings of Ani, and after the surrender of Ani by Gaghik II to the Byzantines, they transferred their alliegence to Constantine IX Monomachus. A cousin of Apellarib, a son of Gregory Magistros, became a Catholic, also taking the name Gregory. It seems the family had a particular attachment to Gregory the Illuminator, the first Armenian bishop who is considered to be the founder of the Armenian church. This would account for the representation of Gregory on this seal, a rare instance of iconography of this saint.
See also front cover illustration