<p>The surface inlay technique has been extensively utilized in the fabrication of traditional metal artifacts. In China, a unique decorative method involving powder-based copper inlay on steel blade surfaces has been identified. This technique is fundamentally distinct from the conventional copper inlay processes previously reported in the literature. However, it has not yet been comprehensively investigated in academic research. In this study, the technique was characterized using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), microhardness testing, and electrochemical measurements. The results reveal that the brass decorative motifs were successfully bonded to the steel blade substrate through the liquid-state brass inlay technique, forming a stable brass-steel interfacial zone. Microstructural observations indicate that no obvious diffusion layer or Fe-Cu transitional zone is present at the resolution of SEM/EDS. Microhardness testing indicated a clear hardness gradient across the different zones: steel blade substrate (314.2 ~ 341.4 HV) &gt; interfacial zone (119.4 ~ 214.8 HV) &gt; brass inlay zone (117.1 ~ 120.9 HV). Electrochemical results show that the brass-steel interface exhibits higher corrosion current density (<i>i</i>_corr = 24.496 μA·cm⁻²) and lower polarization resistance compared with the adjacent single-material zones (10.789 ~ 21.916 μA·cm⁻²), indicating relatively lower corrosion resistance. The corrosion rate values show a consistent trend. The corrosion resistance of the three zones followed the order: Zone C (brass inlay) &gt; Zone B (steel blade substrate) &gt; Zone A (brass-steel interface). These features collectively provide a set of microstructural indicators for identifying this technique in archaeological materials. These findings provide new insights into the mechanism of powder-based copper inlay and contribute to the reconstruction and interpretation of traditional metallurgical techniques.</p>