Emperor: The Field of Swords by Conn Iggulden

the arms bare. He smiled as they pulled them on, used by now to following his instructions without question.
        “You will need the protection,” he told them as they struggled to move against the constricting coverings. At his signal, his sons used tongs to lift the cover from the charcoal pan and Cavallo pulled the yellow blade from the furnace with a flourish. The Roman smiths crowded closer, knowing they were seeing a stage of the process they did not recognize. Renius had to step back from the sudden wave of heat and craned to watch what was going on.
        In the white heat of the charcoal, Cavallo hammered the blade again, sending sparks and whirring pieces of fire into the air. One landed in his hair and he patted the flame out automatically. Over and over he turned the blade, his hammer working it up and down without the force of his first blows. The ringing sound was almost gentle, but they could all see the charcoal sticking to the metal in dark crusts.
        “It has to be fast here. It must not cool too far before the quenching. Watch the color… now!”
        Cavallo’s voice had softened, his eyes filled with love for the metal. As the redness darknened, he lifted his tongs and jammed the sword into a bucket of water in a roar of steam that filled the little workshop.
        “Then back into the heat. The most important stage. If you misjudge the color now, the sword will be brittle and useless. You must learn the shade, or everything I have taught you has been wasted. For me, it is the color of day-old blood, but you must find your own memory and fix it in your minds.”
        The second sword was ready and he repeated the beating in the charcoal bed, once again scattering embers into the air. It was clear enough by then why they wore the leathers. One Roman grunted in pain as a fiery chip settled on his arm before he could pluck it away.
        The swords were reheated and shoved into the charcoal four more times before Cavallo finally nodded. They were all sweating and practically blind from the moisture-laden fog in the workshop. Only the blades cut through the steam, the air burning away from their heat in clear trails.
        Dawn lit the mountains outside, though they could not see the light. They had all stared into the furnace for so long that wherever they looked was darkness.
        Cavallo’s sons covered the tray and dragged it back to the wall. As the Romans breathed and wiped sweat from their eyes, Cavallo shut up his forge and removed the bellows from the airholes, hanging them neatly on hooks ready to be used again. The heat was still oppressive, but there was a sense of it all coming to an end as he faced them, holding a black blade in each hand, his fingers wrapped around a narrow tang that would be encased in a hilt before use.
        The blades were matte and rough looking. Though he had hammered each using only his eye, they were identical in length and width, and when they were cool enough to be handed around, the Roman smiths felt the same balance in each. They nodded at the skill, no longer resentful of the time they had spent away from their own forges. Each of them realized they had been given something of value, and they smiled like children as they hefted the bare blades.
        Renius took his turn with them, though he lacked the experience to be able to judge the weight without a hilt. The blades had been taken from the earth of Spain, and he stroked a finger along the rough metal, hoping he would be able to make Julius understand the glory of the moment.
        “The charcoal bed gives them the hard skin over a softer core. These blades will not snap in battle, unless you leave impurities within, or quench them at the wrong color. Let me show you,” Cavallo said, his voice stiff with pride. He took the blades from the Roman smiths and gestured them to stand back. Then he rapped each one hard onto the edge of his forge, causing a deep tone as if a bell