Exif Editor is an application that allows you to edit metadata in directly your photos.
The tool is useful when you don't want to expose camera to your customers. When your RAW processor doesn't open your file because it doesn't recognise valid camera/lens combination.
In some applications, it's needed to reload metadata as they are heavily cached, for example Adobe Bridge, Lightroom or Aperture. Adobe Lightroom - select image, right click and in the popup menu select Metadata->Read Metadata from Files.