References for the Seattle Art Sword Token Kai meeting
I have found these two sites to be excellent resources for research and interesting stuff about Nihonto:
https://markussesko.com/kantei/
http://www.sho-shin.com/contents.htm
I referred to them extensively while putting together my talk. I also used a number of books from my own reference library, but these two sites are out there and available. I highly recommend them.