There is a violin song played in Attack on Titan episode 39 (season 3 episode 2) from 13:00 to either 13:42 or 15:00 (not sure when it ends).
It's when Armin just killed someone to save his friend and he is sad and talking about it, Levi starts talking. Right after Levi says "arigato (thanks)", it starts playing.
It is also in episode 44 around 13:54.when Historia says that she will eat Eren... I think I've heard it before in season one too.
What is this song?