3 week old weasel. How do i take care of it?
I think kits need their mothers till around 6 weeks after that you can get high nutrient ferret food which should work for you. Make sure fresh water is always available and try soaking the food in warm water to soften it.
Here's some info: http://en.wikipedia.org/wiki/Weasel
I would also ask the Vet and Pet Stores for info.