@oriongu, I had a hunch so I dug into your merged sword asset and validated my hypothesis. The normals of your vertices are inverted so they all point inward. It’s most obvious in the handle as the vertices on the blade are at the edge so knowing which of the split vertices is rendering each normal line is not that clear.
They should be pointing out for the lighting calculations, but you have them pointing in which means the back faces, while rendering, are not lit by the scene lights.
If you just reverse the normals on your mesh, it should render correctly. Hope this helps but ping back with more questions.