This is Mahishasuramardhini, a form of Durga. Here she is slaying the asura (demon) Mahisha and hence the name. Mardhini is one of the widely worshipped Hindu goddesses.
Mardhini is plunging Trishul into the demon’s chest while yanking him out of the buffalo’s body. Her right leg pins the buffalo’s body to the ground. The rear hands are holding sword and shield. The severed head of the buffalo is on the front of the peetha. Notice the smile on her face and crescent moon on the crown.
This bronze is most likely from Orissa region, the peaked crown, ridged Trishul and beads on the top part of the base lead us in that direction.
Mardhini with sword and shield is less common among bronzes from Orissa. But most of the four-armed Mardhini’s you come across, from Himachal Pradesh, Maharashtra and Karnataka, depict her with sword and shield.
According to T E Donaldson in ‘The iconography of Vaishnava images in Orissa”, Mardhini was depicted in Orissa with sword and shield till Vaishnavism gained strength in 9th-10th century.
On this site, there is an example of Mardhini from Orissa holding discuss and conch in her rear hands and plunging Trishul, held with both front arms, into the demon’s chest. I have included photos of the two Mardhini’s for comparison. The similarity of these two bronzes is remarkable.
This bronze is about 10 cm in height. The patina is whitish and the natural colour, brass/bronze, is showing at the ‘high points’. Quite likely this was immersed in water for a long time. This bronze may date earlier than the eighteenth century.