Blender Internal : trouble with custom normals shading

Hello everyone. I was playing around with normal editing via Blender4Web addon. So I’ve created a sphere with node material and edited normals (Picture 1). My target is to make this area be lit or shaded instantly. It actually works, but there are lamp angle (about 1 degree) where it becomes half shaded (Picture 2). How can I get rid of that half shading? I need only 100% shaded or 100% lit areas.