“In a moment of high drama, his aged father hurled himself on the ground at Gregory’s feet, and cried ‘My son, where are you going? Shall I ever see you again?’
‘It is written,’ Gregory answered, as he stepped over the obstacle, ‘ that thou shalt trample on the ass and the basilisk.’
Thus saying, he mounted his mule, which started to walk backwards. Eventually, another animal was brought, and the pope was able to start out for Marseille, the scribes, lawyers, engrossers, and bullatores of the Papal court dribbling along behind him with their piles of parchment, documents, seals, ribbons, and all the other material of the spider’s web that Avignon had woven around Christendom.”
— Frances Stonor Saunders, Hawkwood: Diabolical Englishman
An engrosser is either someone who seeks to obtain a monopoly in a limited market, or someone who makes illuminated manuscripts. In the context of this sentence I would say that either meaning is equally likely. After a little research, I have no idea what a bullatore is, though it’s probably related to a bulla, which is the round seal used to stamp papal documents (bulls).