Nice work!
I have used hairgrips/bobby pins to make sword blades and being steel they are slightly more 'solid' than copper.
I also replaced the naginata's with steel ones using the Foundry steel spears and hammering a section flat to be ground into the blade shape.
Copper wire once hammered can be very very sturdy. For me it combines the best elements. Easy to flatten, it can be bent to the exact shape you need, easy to file shape. Putting on the ''edge'' of the blades there was alot of handling involved and they never bent out of shape. In some cases I overdid it so much with sharpening that I managed to stab/cut myself afew times
That wakizashi of Retsudo is lethal in real life