This isnt really to find in early game. You can get the moonlight greatsword from seaths tail which is obviously in the late game.
you could of course hunt the embers early. You can get the divine ember very early on. After Andre just go for the forest and kill the moonlight butterfly and in the building there is the divine ember. Not sure who to give to, but with this you can upgrade your weapon to divine. Which will then level with faith. There is an ember for intelligence too, just google it. Most Weapons can be upgraded with this.