Saint Justina of Padua
Detail from the San Luca Altarpiece, Pinacoteca di Brera, Milan
Following the usual iconography, the saint is shown with her eyes cast to Heaven in prayer and a short sword piercing her breast (her "side" in the Latin of the story). This was the way St. Justina of Padua died. The other notable Justina, whose attributes include a cross and a demon, was beheaded in Antioch.
More of St. Justina
Source: Web Gallery of Art