Potnia was the most important goddess in Greece in the Late Bronze Age, which is called Mycenaean (1600 - 1100 BCE). She is mentioned on the tablets with Linear scripts B from Knossos and Pylos as PO-TI-NI-JA with many epithets. Some of these adjectives are of local provenience, where some of them characterize the sphere of her influence.
In Mycenaean monuments, Potnia appears with many attributes: the snakes, the double axes, the lions, the doves, the griffin, as well as other kinds of animals and sacred features. Sometimes standing alone they have to indicate the presence of the goddess.
Potnia is the protector of nature, vegetation, fertility and in this case she is closely related to the Minoan Mother of the Mountains. During Late Helladic III period (after 1400 BCE) Potnia is depicted more war-like. Armed with weapons, wearing a helmet, she is accompanied by the griffin.
J.Chadwick believes that Potnia was connected with the cult of the Earth Mother, dominated from Early Helladic time over all Aegean religion. He supposes this cult continued with a variety of names into the classical period. M.P. Nilson presumed the role of Potnia in Greek classical religion was taken over by Athena, Rhea and Hera.
I think the position of Potnia and her attributes were changing in the harmony with needs of Mycenaean community. Beside her primary function of the goddess of nature, vegetation and fertility, she had to be powerful and warlike to protect Mycenaean palaces and their cities against the enemies. That is why Mycenaeans paid great attention to the weapons, showing Potnia with helmet or sword, and it is not to be wondered that one adjective of Potnia on the tablet from Pylos was connected with bronze-smiths. In Greek Olympian religion the place of Potnia disappeared. Her role and her divine attributes spread out between many goddesses.