The BladeForums.com 2024 Traditional Knife is ready to order! See this thread for details:
https://www.bladeforums.com/threads/bladeforums-2024-traditional-knife.2003187/
Price is $300 $250 ea (shipped within CONUS). If you live outside the US, I will contact you after your order for extra shipping charges.
Order here: https://www.bladeforums.com/help/2024-traditional/ - Order as many as you like, we have plenty.
Not a derringer but, a NAA mini-revolver in 22Mag packs a real wallop. .
If I absolutely had to limit myself to a derringer http://www.bondarms.com/ would be where I'd start looking.
Also as to the .410..really not a defensive load at all.http://www.theboxotruth.com/docs/bot41.htm
I will put my vote in for the NAA .22Mag, small, light and has close to the the same ballistics as a .38 Special.