From Europa [translated]:
An armed priest, detained at one of the entrances to St. Peter’s Square hours before the Angelus on Sunday: Italian police officers arrested on Sunday morning, hours before the Angelus prayer, a priest dressed in a cassock at one of the entrances to St. Peter’s Square in the Vatican armed with a compressed air pistol, two knives, a cutter and a screwdriver.
From Catholic News Agency:
According to Europa Press, the weapons were in a bag that belonged to another man, a 60-year-old Czech who accompanied the priest and who was also detained. Neither has a criminal record and both came to Rome on a pilgrimage from the Czech Republic.