Recently Ubisoft published a gameplay, in which you can see how christian knights use the sword by taking it by the razor and hitting the other warrior with the handle (I would post the link but I don't know if I'm allowed). So has that any actual logic or was it actually used in the Middle Ages or is it just plain stupid and put in the game because it looks "cool"?
There are 15th century German fighting manuals (Hans Tallenhover's Fechtbuch or fight book) illustrating and showing captions that depict these kind of strikes in use. They were a technique that was apparently used by European swordsman reasonably often.
I don't know enough about the subject to explain why this particular strike is advantageous. There are a number of users on ask historians that seem to have a deep knowledge of historical european swordfighting and perhaps one of them will produce a more detailed reply.