In Iliad 5.733-7, Homer describes how Athena took off the finely-wrought robe 'which she herself had made and worked at with her own hands' and 'armed herself for grievous war'. This incident encapsulates the paradoxical nature of a goddess who is as skilled in the preparation of clothes as she is fearless in battle; who thus unites in her person the characteristic excellences of both sexes. At the greater Panathenaea in Athens, she was presented with a robe, the work of maidens' hands (...), which traditionally portrayed that battle of the gods and giants in which she was the outstanding warrior on the side of the gods.
Her patronage of crafts is expressed in cults such as that of Athena Ergane, Athena the Craftswoman or Maker; it extends beyond the 'works' of women to carpentry, metalworking, and technology of every kind, so that at Athens she shared a temple and a festival with Hephaestus and can, for example, be seen on vases seated (in full armour!) in a pottery. Her love of battle is seen, as we saw, in myth, and also in cults such as that of Athena Victory (Nike); she is regularly portrayed fully armed, one leg purposefully advanced, wearing her terror-inducing aegis.
She is also closely associated with the masculine world in her mythological role as a helper of male heroes, most memorably seen in her presence beside Heracles on several of the metopes of the temple of Zeus at Olympia. Indeed, her intervention in battle often takes the form of 'standing beside' a favourite (e.g. Il. 10.278-94) . . . Her virginity is a bridge between the two sides of her nature. Weaving is a characteristic activity of ordinary young girls, but a perpetual virgin, who is not subject to the distinctively feminine experience of childbirth, is a masculine woman, potential warrior.
The warlike Athena is scarcely separable from Athena Polias, the goddess of the Acropolis and protectress of cities. 'City-protecting' was most commonly performed by goddesses rather than gods; and that other great protectress was the other great warrior-goddess of the Iliad, Athena's close associate Hera. Athena exercised this function in many cities besides Athens, including Sparta and (in the Iliad) Troy. Athens was unique only in the degree of prominence that it assigned her in this role.
A few cult titles and festivals of Athena seem to indicate interests other than those discussed so far; and it has often been suggested that her familiar classical functions have been pared down from a much broader original competence. But this is too much to deduce from stray allusions to cults the details of which are usually very little known. The 'Athena Mother' of Elis (Paus. 5.3.2) is a puzzle; and Athena's limited intrusions upon the preserves of other gods at Athens - the cult of Athena of Health (Hygieia) for instance - may simply reflect a tendency of city-protecting gods to have a finger in every pie.
Athena is unique among Greek gods in bearing a connection with a city imprinted in her very name. The precise linguistic relation between place and goddess is teasingly difficult to define: the form of her name in early Attic inscriptions is the adjectival Athenaia, which suggests that she may be 'the Athenian' something, the Athenian Pallas, for instance (Pallas Athenaie being a regular Homeric formula). But this account still leaves the shorter name-form Athena unexplained. Athenians themselves, of course, stressed the goddess's association with their city enthusiastically. She was the foster-mother of the early king Erechtheus/Erichthonius, and had completed, successfully, with Poseidon for possession of Attica. In Panhellenic mythology, however, she shows no special interest in Athens or in Athenian heroes. The association with Athens does not appear to affect her fundamental character.
Her most important myth is that of her birth from the head of Zeus. It stresses her unique closeness to Zeus, a vital quality in a city-protecting goddess, and at the same time the gap that divides her, a child without a mother, from the maternal side of femininity. In the oldest version (Hes. Theog. 886-90) Zeus became pregnant with Athena after swallowing Metis; she was thus also a kind of reincarnation of metis, 'cunning intelligence'.
It has in fact been suggested that Athena's characteristic mode of action, a mode that unifies her apparently diverse functions while differentiating them from those of other gods with which they might appear to overlap, is the application of metis. Her metis appears obviously in her association with crafts and in her love (Hom. Od. passim) for wily Odysseus; more obliquely, it is argued, it is for instance to be seen in her title Hippia, 'of horses', which she acquires via a product of metis, the bridle, whereas Poseidon Hippius embodies the animal's brute strength. In warfare she would express rational force, vis temperata, in contrast to the mindless violence of Ares. One may doubt, however, how fundamental the opposition to Ares and the role of metis in fact are in defining her military function.
Precursors of Athena have been identified in Mycenaean military or palace-protecting goddesses; the only solid evidence is a tantalizing reference in a Linear B tablet from Cnossus to A-ta-na po-ti-ni-ja.
Robert Parker, 'Athena', The Oxford Classical Dictionary, Third Edition, 201-2.