Salve Draco,
I agree with you that Svantevit indeed sounds Scandinavian but it is truly a Slavic word. The stem "svet, swant or svent" means holy, mighty, powerful. "-vit" is derived from "vitez" meaning lord, victor.
In Norwegian "svane" means swan (Schwan in German). And I know of the Scandinavian name Svanhild.