Short answers, pulled from the story.
In Ancient Rome, the pileus was placed on the shaved head of a slave during the legal ceremony of manumission, marking the moment of freedom. It served as a symbol of Libertas, the goddess of liberty, alongside the vindicta rod used by the presiding praetor. Coins of Antoninus Pius struck in 145 AD depict Liberty holding the cap.
The pileus cornutus was a pointed variant of the pileus cap imposed on the Jewish people of the Holy Roman Empire as a compulsory distinguishing sign. It was worn from the 12th through the 17th century, spanning roughly five centuries.
The earliest preserved specimen of the Pannonian pileus was found at Mons Claudianus, a Roman quarry in the eastern desert of Egypt, and dates to 100-120 AD. It is dark green and resembles a low fez or pillbox hat.
The Albanian traditional felt cap, the qeleshe, originated from a similar cap worn by the ancient Illyrians. The Albanian word plis is considered cognate with Greek pilos and Latin pileus, all sharing a common Proto-Indo-European root meaning felt.
The pilos helmet developed from the 5th century BC onward, cast in bronze in the same conical shape as the felt cap of the same name. Historians believe the original felt hat was sometimes worn underneath the helmet for comfort, which gave the helmet its distinctive shape.
Servos ad pileum vocare means a summons to liberty, a call to slaves to take up arms with a promise of freedom. The phrase draws directly on the pileus cap's established role as the symbol of manumission and liberty in Roman culture.