The damp, cold neon rain lashes the rusted alleyways of the Lower District in Xinyu City 🌧️🔹, as modified mercenary A Yan leans against a leaky billboard, wiping down his new blade 🗡️. This all-sky-blue training tactical dagger was 3D-printed by a black-market printer using high-hardness polymer filament🔧; its streamlined, ripple-patterned handle is perfectly matched to his neural-implant prosthetic arm, while the hollowed-out serrated spine is designed to snugly accommodate the prosthetic’s signal-sensing module📟, enabling real-time synchronization of force data to the terminal during training so he can adjust his fighting stance on the fly. Tonight is the final of the Lower District’s underground black-market fighting tournament🤜🤛, and his opponent is a cybernetic assassin dispatched by a corporate conglomerate, clad head-to-toe in carbonized alloy armor⚙️. A Yan slides the blue blade into the slot for his prosthetic arm, and the venue’s pinkish-purple neon spills over the matte-blue blade, scattering a chilling glow✨. Within three seconds of the opening bell, the assassin’s alloy slashing blade shatters A Yan’s defense, and the blue blade precisely locks into the seam of the assassin’s cybernetic shoulder plate⚡, its serrated spine firmly gripping the transmission conduit. Suddenly, the arena’s control screen flashes a red warning—corporations have long rigged the match to eliminate any freelance mercenaries who refuse to sign contracts🔴. A Yan presses down with force, bending the blue blade into a subtle arc, and tiny sparks erupt from the seam🔥. No one could have imagined that an unassuming training blue blade would become the very first needle to pierce the corporation’s dark veil…