A penn no weightier nor a polepost

• The pen is mightier than the sword: Edward Bulwer-Lytton (1803-1873), Richelieu, Act 2, Scene 2
  • Wikipedia

• Pen → in FW Shem is the writer of the letter, hence he's the pen-man ("Shem the Pen")

• Post → in FW Shaun delivers the letter, hence he's the post-man ("Shaun the Post")

• penna: (Latin) feather → in the Egyptian Book of the Dead (boke of the deeds two lines below), during the Judgment of the Dead by Osiris, the heart of the deceased is weighed in a balance against a feather to see if it is heavy with sin

• wittier

• goalpost

• Libra: the zodiacal constellation of the Balance → the weighing of the deceased's soul in a balance in the Egyptian Book of the Dead

• Penn: William Penn, English Quaker who founded Pennsylvania
  • Third Census of Finnegans Wake

Commentary

This line invokes the epic struggle between the two sons of HCE: Shem (File:Shem.png) and Shaun (File:Shaun.png).