The Southern Ritual Band increases the amount of attunement slots a player can have. One for the basic, two for the +1, three for the +2.
The +1 variant can be found in a chest in the Brightstone Cove Tseldora. From the bonfire after the chapel go along the path, until you find a zipline. Go down the zipline, and into the nearby house. Once through, drop down onto a ledge where a Hollow Mage is. There is a house you must enter, and pulling a lever will lower the chest where the ring is hidden.