The Kill Bill replica swords in this collection are crafted from different carbon steel grades depending on the specific piece. The Bride Katana uses 1045 high-carbon steel with a clay tempering process, which produces a visible hamon — the temper line that is a hallmark of traditional Japanese blade-making. The O-Ren Ishii Shirasaya uses 1065 carbon steel, a slightly higher carbon content that results in a harder, more refined edge geometry suited to a display-oriented collectible. The Red Blade variant is built from folded Damascus steel, a pattern-welded construction that creates distinctive surface layering. Each steel choice reflects a different facet of Japanese sword craft, giving collectors meaningful options based on their aesthetic and material preferences.