Hello Russel,
I am not sure where and when but I am nearly sure to have seen a sewar scabbard like this before. Your scabbard don't look recarved to my eyes.
I think that the blade was cleaned to reattach the the handle without rust at the tang.
Don't worry to much about etching a blade, try lemon or vinegar, you can't do mistakes by this.
Again, great score by this beautiful sewar!
Regards,
Detlef