Some of you may think that this its very odd for people to like these kinds of stuff but really, collectors are no harm. It's the users that you should be worried about. Carriers are probably equally dangerous but only carry for security purposes.
Trivia: Boxers back in the day usually slip in one of these knockers in illegal boxing matches. As well as old-school gentlemen who get home late from work, anticipating the hoodlums in alleys or stray gangs. Soldiers during the two world wars also favor this weapon for personal use and possible "self-expression" for the enemies. Another version of this is the "trench knife."
Props to Weapon Collector for the picture and ownership. Just had to share this. Stunningly beautiful work, literally and figuratively.