After examining the sword a bit more, he dismissed it and closed his eyes once more. He wanted to spend time experimenting with Sword Birth to see how viable so many of his ideas were. His knowledge and experience as an Artificer giving him some unique thoughts on what he might be capable of pulling off.
For the next sword though, he wanted to try to control the materials the blade was made of. Within his mind he imagined a standard executioners sword. The sword had the length of a single handed sword, he chose one hundred centimeters for the length making it longer than expected. The blade also lacked a tip making the blade one long rectangle with sharp edges and a flat top. At the tip of the blade were three holes drilled through it in a triangle pattern. The quillons of the sword were perfectly straight with a basic twist to give them at least a decent appearance. The basic leather wrapped handle was topped with a pear-shaped pommel for counterbalance. Not that it mattered when he imagined the blade widening until it was large enough to qualify as a shield. For the final touch, he imagined the blade being made of Adamantine and focused on all of his knowledge of the magical metal.
With the image fully formed within his mind, Junichiro focused on his faith, his belief, that Sword Birth could make the weapon exactly as he pictured it. After all, unless the Sacred Gear itself refused to make the weapon, there was absolutely no reason for him to doubt that it was capable. Even less reason to doubt with what he knew of its abilities and functions. Yes, he fully believed he could create the massive Shield-Sword as he fed his magical power into the image.
It took a while, much longer than the first blade, but Junichiro never lost his faith in his Sacred Gear and continued to feed it power until he felt the same 'click' as he had before. With a brilliant flash of golden light, the massive Shield-Sword appeared in his hand. Naturally, he instantly lost control of the sword as the huge and heavy blade was pulled out of his grip by gravity and slammed into the floor.
Junichiro took a few seconds to catch his breath while visually inspecting the huge weapon. It put a weapon like the classic Buster Blade to shame with how wide it was. It'd definitely take someone with supernatural strength to lift the thing and use it as an actual Sword. Junichiro merely intended to use it as a Shield that he could summon as needed to take a few hits. Still, the summoning took a fair bit more magical power than the previous one so he firmly believed he'd succeeded.
To prove he succeeded, he touched the blade and channeled his power through it after he caught his breath. A wicked smiled slowly curled his lips as the metal came back as Adamantine. It still suffered from the same feeling of a thin existence, but it was definitely Adamantine so it should be able to take significantly more damage than the steel sword. In fact...
Junichiro lifted the Executioner's Shield Sword up and set it against the table so it was standing up with the flat tip against the ground and the handle at the table's edge. With the massive blade propped up, he held his hand out and summoned his basic longsword in a flash of white light once again. Summoning it the second time actually felt like it took less magical power. He wondered, briefly, if the first time a sword is created and summoned took more energy than future summons. Something else to experiment with.
He pushed that experimental thought to the side and lifted the longsword up to grip it with both hands, one on the handle and the other holding the pommel for more power. Both of his weapons had the same thin existence, but would the Adamantine one prove to be more durable than the steel one? To find out, Junichiro swung the longsword in a powerful horizontal slice aimed right at the Executioner Shield's edge.
He felt the jarring impact of the two blades colliding together and grunted. The impact barely moved the much larger and heavier weapon but hadn't broken either one. He smiled and cocked his arms back to take another swing. It took over a dozen blows before the steel longsword shattered into pieces that dissolved into white light. Junichiro blinked at he noticed the different coloration of the light. The Executioner's-Shield had been made in a golden light, right?
Something else to look into! He dismissed that for now though. He focused on the Executioner's-Shield and channeled his power through it. A grin slowly grew on his face as he could feel that the sword's existence had become even thinner. He estimated it was maybe half what it was previously? Sword the Adamantine sword was clearly stronger and more durable than the steel, as it should be, and the summoned swords had a sort of durability system built into them. He was also clearly wrong about a normal human not being able to break them. He was not just a rather normal human, but also a teenager. Sure, he was strong for his age and his right arm gave him a strength advantage, but still... Well, he had no problem with being wrong about something. It happened frequently with alchemy potions anyway.
He waved his hand, an unnecessary motion, and dismissed the Executioner's-Shield. When it vanished in a flash of golden light, he pondered the meaning of the difference. Obviously his first conclusion was that the difference in the light color was down to the difference in the materials used in the weapons themselves. Mundane material versus magical material.
So, he now had two swords and the only thing special about any of them was the one was made of a magical metal. Now, what about a magical sword? He closed his eyes once again to focus. He smiled when he 'saw' the two swords he'd designed stored within Sword Birth, he could summon either one with just a thought and a burst of magical power and didn't need to focus on their details. Such a wonderful feature. For his third sword, he focused on a basic longsword, similar to the first, but added the ability for the sword to produce flames that covered the blade to add some fire damage to the weapon.
Once the image was firmly held in his mind, he sent magical power to Sword Birth while opening his eyes. A familiar looking longsword appeared in a flash of white light. A quick check showed that channeling power into it would ignite the blade and doing so coated the weapon in roiling red flames. Though Junichiro found it interesting that the magical weapon glowed white, not gold. So, just the difference in materials?
He dismissed the weapon and focused on making another flaming longsword. However, this time he focused heavily on the material the blade was made of. He choose to construct the entire thing of Hihi'irokane, a classical Japanese fantasy metal that actually existed and had close ties with fire, it was known as the 'flame-colored metal' after all. It did feel a bit sacrilegious to be using an Eastern metal to make a Western sword, but whatever. It was all about the relationship of the metal to the magical enchantment that mattered for this.