I went to the sword museum here in Tokyo as part of a group guidance, it was super interesting:
- forging a sword takes 6-10 days
- these are not stainless. When signs of rust appear, grindstones are used. Not regularly, just needed - as it wears down the blade
- brides in samurai families got a small sword as gift when entering the marriage, to kill them self if needed
- swords had tools attached like picks to clean ears or scratch the head
- swords often got reworked to fit new fashion/style