Nether Star Mace Sword

Implement only these approved requirements: - Register one custom sword tool with durability 800, attack damage 10, attack speed 0.35, enchantability 20, mining speed 6, mining level iron, and the default iron repair tag. - Represent the requested mace-like visual design as the sword's inventory texture: a mace-shaped weapon with a subtle star in the middle inspired by a nether star. - Create the nether_star_mace_sword texture: Minecraft item texture for a custom sword shaped like a compact mace, with a dark metallic handle and head, and a small bright nether-star-inspired star embedded in the center. Pixel-art style, clear silhouette, transparent background.