No offense to your karate instructor, but he's seriously misinformed and is passing along bad information.in my karate class we have been told a saber is not the same as a sword it is a big knife
what is the difference between a saber and a sword
A sabre is a type of backsword, usually but not always curved, and usually single edged, though some have a false edge, sometimes a partial false edge. I've attached a picture of a USMC sabre for reference.