Interesting. I had not seen that reference before, nor have I seen any references relating to early Highland military uniforms (especially in the Independent Companies) that mentions badges.

This is pure conjecture, but badges may have been issued in the context of modern police badges, i.e., to certify that the individual Highlander was indeed a member of an Independent Company, who in those early days were 1) engaged in law enforcement activities and 2) may not yet have been fully uniformed in red coat, Government tartan, etc, for identification purposes. I can imagine that a problem may have existed from unscrupulous Highlanders attempting to pass themselves off as Independent Company members to gain some sort of advantage over prospective victims.

What form did these blazons/badges take? Has anybody seen one? To the best of my knowledge, Highland regiments didn't start putting regimental numbers/titles (except for regimental names and rack marks on muskets, bayonets and swords) on regimental uniform items until the American War of Independence.