THAT IS SOMETHING I HAVE OFTEN WONDERED ABOUT TOO. I HAVE SEEN MANY EXAMPLES OVER THE YEARS AND IT SEEMS UNLIKELY THEY WERE ALL DONE BY AMATEURS WHO TOOK OUT A BLADE AND PUT IT BACK IN WRONG ACCIDENTALLY. NOT MANY COLLECTORS OR ADVENTURERS WHO BROUGHT BACK A SOUVENIR OR WAR TROPHY EVER TOOK OUT THE BLADES AND REMOUNTED THEM. A LOCAL MORO SWORD SMITH WHO MADE, REPAIRED AND SOLD SWORDS REGULARLY WOULD NOT BE MAKING MISTAKES.
EACH INDIVIDUAL OR SCHOOL HAD THEIR OWN FIGHTING STYLES WHICH ARE MOSTLY UNKNOWN TODAY SO SUCH A VARIATION OF BLADE ORIENTATION MAY HAVE BEEN USED. PERHAPS THEY HAD SOME WARRIORS LIKE SOME NORTH AMERICAN INDIANS WHO DID EVERYTHING BACKWARDS. EVEN GOING SO FAR AS TO RIDE THEIR HORSE FACING BACKWARDS A HANDY THING IF SHOOTING AT ENEMIES WHO ARE CHASING YOU.
DISCLAIMER (THIS MAY BE A STORY MADE UP FOR WESTERN MOVIES OR A REAL STORY ?)
OFTEN WE ARE TOO QUICK TO JUDGE THINGS BASED ON A NORM OR ON EXAMPLES FROM THE FEW REFERENCE BOOKS AVAILABLE.