Maybe the ring is some twisted way the manga brings in svanhild from the same legends who was kriemhilds daughter iirc. Technically Lynn os her daughter cuz she was born from her wish
"Svanhildr is the beautiful daughter of Siegfried and kriemhild in Germanic heroic legend, whose grisly death at the hands of her jealous royal husband Ermanaric was told in many northern European stories, including the Old Norse Poetic Edda" sieg is dead so svanhild can never be born conventionally after all and sieg and kriem discussed ger wish together in bed
