She was supposedly a winged tongue that could actually sing the defeat of her enemies into existence. Someone that powerful and who has wings? The last person, or thing we know of that was winged and powerful like this was called a child of Kyne, and was. Morihaus, the father of Minotaurs.
Barfok, sounds far more powerful, godly, and like a literal Valkyrie in TES, but the only account of her we have is in the 36 lessons, which of course means it could be mere flight of fancy on Vivec’s part. But, if you’ve read the 500 companions, you know the Nords/Atmorans were a very strange and diverse bunch. One guy even shouted himself into a woman by accident. They also had giant-folk, and offspring of giantfolk and atmorans. A child of kyne blessed with wings and great talent with the thu’um isn’t even that strange for them really. Or for that time period in Tamriel. This kind of stuff just happened.