"The two most commonly attributed phrases "devils in skirts" or "ladies from hell" appeared to have been applied to the 51st Highland Division during the First World War and both expressions appear to be interchangeable. It was German intelligence, which like the British kept a record of those enemy divisions that were opposite them in the line. Some divisions fought harder than others, with the 51st joining the top of the German list, after the clearing of the Y Ravine in the autumn of 1916. The two expressions became popular around this time amongst the German soldiers, who were as fond of nicknames as the British Tommy. With time, it has become applied to all Scottish regiments that wear the kilt, whether in battle or on the parade ground."

Sounds more like attributing a mark of "healthy respect" by German troops rather than being some sort of ploy by the Allies to "strike fear into the hearts of the German enemy."