I WOULD THINK THE LEAVES ARE THERE FOR CEREMONIAL PURPOSES, VARIOUS KINDS OF LEAVES ARE USED FOR DIFFERENT THINGS THE WORLD OVER. THE LEAVES LOOK LIKE TI LEAVES TO ME RATHER THAN BAMBOO AND THERE MAY BE MORE THAN ONE TYPE OF LEAF ,DIFFICULT TO TELL FROM A PICTURE. THE TI LEAF IS USED IN VARIOUS CEREMONYS AND TO PLACE OFFERINGS ON THE MAIRAE (ALTER) IN OLD HAWAIIAN CEREMONYS. THERE ARE ALSO SPECIAL LEAVES USED IN BORNEO TO PLACE ON THE HEADS TAKEN IN HEADHUNTING DAYS, THERE IS A RITUAL SUPPOSED TO BE PREFORMED EVERY YEAR TO REPLACE THESE LEAVES.
IF NOT CEREMONIAL THEY COULD BE THERE TO USE TO WIPE DOWN THE BLADE WHEN IT GOT DIRTY OR WET, A MORE EXOTIC CONJECTURE WOULD BE THAT THEY WERE POISON AND COULD BE WIPED ON THE BLADE JUST BEFORE A FIGHT. ALL JUST GUESSES
A NICE OLD EXAMPLE BUT IT LOOKS LIKE THEY SHOULD HAVE WIPED THE BLADE WITH DRY LEAVES MORE OFTEN.
