Using logic and common sense: The SS man himself declares that he was NOT entitled to carry an honor dagger, so there are 3 solutions possible (assuming it is not parts dagger):
1. According to the SS number stamped on the crossguard the dagger belonged to him and the dedication is post war.
2. Dedication is original to the blade and whole dagger, but the number was added post war.
3. Both dedication and number are post war done to enhance the value

Is there any other option? Sorry, but "it comes from the dealer = it must be authentic" is worth to me as much as "they told it on TV = it must be truth".