The truth of the matter is, the VAST majority of sgian dubh out there are made for show / decoration only and are NOT meant to be used as actual blades. They have tangs that are both too thin and too short.

A full length hidden tang, with some meat to it, makes the best sgian dubh if you actually want to be able to use it to cut stuff and not risk breaking the handle, or snapping the blade off at the stress risers caused by the sharp angles cut into the back of the blade where the tang meets the blade itself.