Four-Armed Mahakala - The Protector of Wisdom
A four-armed aspect of Mahakala, one of the eight great Dharmasalas, or Dharma Defenders. Also known as the Protector of Wisdom, Mahakala is a wrathful deity who courageously protects the Buddhist teachings and those who study them from harm and evil forces.
Despite Mahakala's always terrifying appearance, he is a Bodhisattva, an embodiment of compassion who acts for the benefit of all sentient beings. His function is to avert the inner and outer obstacles that prevent practitioners from attaining spiritual realizations, as well as to foster the necessary conditions for their practice. It is said that by simply making a wish for protection to Mahakala, a sincere seeker's needs will be met
Gestures and Attributes
Mahakala is depicted in several variations, each with different qualities and accouterments. In most depictions, such as this one of his four-armed form, he wears a crown of five skulls. These skulls represent the transmutation of the five poisons (greed, hatred, ignorance, pride, and jealousy) into the five transcendent wisdoms. He is also seen standing on a human corpse, symbolizing the death of negative patterns and emotions to such an extent that they will never return to life.
He has three faces, four arms, and two legs. His main heads are surmounted by the head of Chakrasamvara, of whom four-armed Mahakala is an emanation. He has three eyes indicating his omniscient knowledge of past, present, and future. Each of his four arms represents one of the special gifts he bestows upon practitioners.
These are:
(1) to pacify sickness, remove obstacles, and eliminate obstructions;
(2) to increase life, stimulate virtuous minds, and enhance Dharma realizations;
(3) to attract all necessary material and financial resources to support disciples; and
(4) to destroy ignorance, confusion and doubt.
In each of his four hands Mahakala holds a special weapon or implement that emphasizes his ability to offer protection and refuge. His upper right-hand holds a flaming sword of wisdom, whose sharp blade cuts easily through delusions and ignorance.
His upper left-hand holds a long staff ornamented with a dry white skull, indicating his ability to subjugate all demons and vicious spirits of the three realms. His lower right hand holds a vajra, symbolizing his diamond-like determination and indestructible power.
His lower left-hand holds a skull cup brimming with the blood of the four maras, indicating his realization of emptiness and his victory over the forces of death. Cradled in his left arm, Mahakala holds a long-long life vase, filled with the nectar of immortality. A rosary of skulls is also draped over this arm, indicating Mahakala's unceasing activity to benefit all sentient beings.
He wears a tiger skin, an elephant skin and snake ornaments, all symbolizing his abandonment of the negative emotions arising from self-grasping. He also wears a long necklace of moist human heads, indicating his abandonment of ordinary appearances and conceptions.
He stands in the warrior's pose with one leg bent and the other extended, surrounded by a blazing fire of exalted wisdom that annihilates all obstacles and consumes all neurotic states.
Source
http://www.shakyastatuestrade.com/pages/ref/Mahakala-FourArm.shtml