The Penitent One's helmet is largely inspired by the Capirote, a ceremonial hat used by some religious groups in Spain during certain rituals and celebrations. The Capirote is also the hat used by The Ku Klux Klan, and is thus often associated with hatred and prejudice.
One of the collectibles 'Sternum of Vitas, the Performer' is a reference to real-life actor, writer and producer Vitas Varnas with the item's description explicitly mentioning his full name.
The Penitent One's sword is named Mea Culpa, which is a real phrase which in Latin means "Through My Fault", and is often used as when one has done something wrong that, symbolizing The Penitent One's pain and struggle for redemption.
The game received a free DLC update called The Stir of Dawn on August 4th 2020, which added new bosses, a new and harder game-mode, as well as new items and abilities.