It's the Eye of Horus. EddardinWinter created the first ProVarinati sigil and used the Eye of Providence. When I created the second version I used the Eye of Horus: 1) because it reduced better for use in signatures; and 2) I like what the Eye of Horus represents over what the Eye of Providence represents and i haz drawed it. Members use whichever they like best, or sometimes create their own.
The version used on the cap was a version of the second sigil with PlanofMan's ambigram added -
ProVarinati reads the same when upside down.
Sigil 1:
Sigil 2:
Cap:
The "L," "S" and "T" in the corners stand for Lumin Sees Totus. It was the Will (cough, fault) of EddardinWinter, ProVarinati Praetor, that our motto (and subsequent native tongue) is fractured EngLatin, untranslatable by the Nonbelievers.