After some researching google-fu and translating, I found out that out of the NPC's list the piece is actually called Slavic by Kirill Pokrovsky on the OST and is also known as Ballad apparently

Seems you can also download the OST of all of the Divinity games off of his website, including Divinity 2's

Might also want to look up Andrea Bocelli if you don't know him already, if your looking for similar music, though that won't be russian.