One of the rarest Martin Handcraft model is the Imperial, a horn that I have yet to get my hands on.  

The pictures show a horn approximately equivalent to the Troubador, but without split bell keys.  

Don't confuse this horn with the Martin Imperial that was produced about the same time as the Committee ("The Martin") horns.  That horn is not labeled Handcraft anywhere on the bell and is a student/intermediate model.

Finally, this horn marks possibly the first Martin model that was introduced before the previous model was officially discontinued. You can call this the "transitional model" Martin, I suppose, similar to the Conn New Wonder Transitional horns.