Complex sentence: It was during his tenure at the Studium in Florence that Chalkokondyles edited Homer for publication, which, dedicated to Lorenzo, Piero de'Medici's son, is his major accomplishment.
Split into simpler sentences: It was during his tenure at the Studium in Florence that Chalkokondyles edited Homer for publication. His edition of Homer, dedicated to Lorenzo, Piero de'Medici's son, is his major accomplishment.