Assuming this idol is from the Hindu pantheon (What else??), the choice is between Surya and Vishnu. The presence of Vanamala (seen on Vishnu figures from North India), the absence of footwear (common in Surya images from North India) and given the fact four-armed Surya is not common, would suggest this is Vishnu.
Here Vishnu is standing on a lotus pedestal in samapada. Features worth noting include the incised halo, beaded sacred thread (see the back view), horizontal bands holding his lower garment, stiff posture and lean features.
The idol is about 14.5 cm in height. The alloy is copper rich. Estimating the age of this, given the paucity of similar examples, is a job for experts. But given the wear, I would think this idol is at least about 500 years old. I am of the view this idol is from North India as in Kashmir or Himachal Pradesh. But then it is only a view.
Again this is one of the idols I could not find enough information on. Well, updates will come.