As you can see on the image above the baked image appears black with exeption to the handle part. I use the free PBR node from Blender Brit for the metal material. The normals are facing the right way. And enabling ambient occlusion didn't solve the problem neighter.
You cannot bake a glossy material. I think that is your problem. By looking at the picture, it appears that the handle is the only thing that does not have a glossy material. Try removing the gloss material from the blade and changing it to a diffuse material. You shouldn't have a problem after you change that.