It might be that Savn is the one who narrates Athyra, at some point after he returns to his village, perhaps a few hundred years later. Given that he suffered brain damage, perhaps he no longer feels quite so connected to the memories of his younger self, which is why the story is told in the third person.
Note that the story follows Savn, and sometimes gives Rocza's internal thoughts. As we see in Orca, Rocza tends to connect rather well with Savn; perhaps she offered her memories of the events of Athyra to help him recover.
There was some speculation that Savn was the potential Lavode that Sethra speaks of in Issola (book). This is no longer considered a likely possibility due to the revelation of Telnan/Zungaron in Dzur (book).