I immediately started to rebuild it with Rike's suggestion. When I forged Nilda's sword, I used the "Kou-bushi" method, in which a soft core iron is sandwiched between a U-shaped piece of hard iron.
　In this case, since the blade is a bamboo leaf-shaped ear, I used a method called "shikata-jime," in which hard skin iron is attached to the soft core iron on all sides.
　Normally, the hardness and softness of steel is affected by various factors such as carbon content and molecular structure, but when I do this, I end up with something that is magically hard anyway.
I'm sure I can achieve "no breakage, no bending," but that's kind of boring too. Therefore, I decided to change the hardness and softness by the amount of magic power applied. The part that will become the skin will be incredibly hard, so it's mostly a matter of mood, I guess.

　I reheat what I was trying to form earlier, and prepare it to become a mere plate. Now that I've put magic into it, I need to put even more magic into it to turn it into an iron skin.
　In the same way, prepare two more sheets of the highest quality iron with magic power. One of them should be split in half lengthwise. Now you have a board that surrounds all four sides.
　The next step is to make a square pillar for the core. This one can be left soft, so after heating it up to an appropriate temperature, I simply beat it quickly to shape it.

All that was left was to put it together. ......

　The sun was already beginning to set, and the sheet metal workers, who had finished their work for the day, were out practicing (and bothering Krull and Lucy). The rhythmic clashing of wooden swords and the chattering of Krull and Lucy could be heard all the way into the forge.

"Let's get to the hardening part.
"Are you sure?

　The only ones left in the room were me and Rike.

At this rate, we'll be able to finish it tomorrow. But it's not good to stop here.
Right.

　I have a vague memory of doing "service overtime" like this in my previous world. It's not a good idea to do a job you love, but it's also not a good idea to continue from here tomorrow.
　So I put the skin iron and the heart iron together in the fire pit and began to heat them. I hear a gurgling sound as the wind gives strength to the flames. The furnace had been turned off, so the sound was even louder.

　In this process, we could not use the same kind of bonding agent that we used in the refolding forging. It would leave a residue between the crust and the core iron. Therefore, when they reach the same temperature, they are taken out and struck together.

Good.

　The red-hot steel is transferred to the anvil. In this process, it is said that there will inevitably be some degree of grafting, but this is not the case, and if the abilities you have been given are fully exercised, you can graft without such grafting. ...... I wonder if this kind of thing will be called an "o-parts" when it is left to future generations. I wonder what people in this world will think of it a thousand years from now, but of course I won't get to hear it.
　Feeling a little sad, but also excited, I put all my energy into the hammer.
　I move the hammer rhythmically, heat it up, and hit it again on the anvil. The process is repeated, and eventually a rather flat steel square bar is produced.

"Well, that's it.
You're still working fast, aren't you?
Well, I know exactly where to hit. ......

　It's true. It is true. I "sort of" know. In other words, I don't know more than vaguely.
　But that seems to be the goal for Rike.

"I have to reach the master's feet as soon as possible.

　I have to reach my master's feet as soon as possible.