Answer:
The only day (at least in European cultures) that is named after a goddess is Friday. In the romance languages, the word for Friday refers to Venus, who was the goddess of love, not the goddess of war. In English, it refers to Frigg/Freyja (it's not absolutely clear which of them was meant, or even whether they were actually distinct goddesses). Neither of them was explicitly a goddess of war (they were more associated with beauty, love, childbirth, and things like that), though given that they were part of the same culture that gave the world both vikings and berserkers, it's not too much of a stretch.