Differential tempering is obtained by quenching the sword uniformly, then tempering one part of it, such as the spine or the center portion of double edged blades, with a torch or some other directed heat source.
Differential tempering is obtained by quenching the sword uniformly tempering one part of it. This was then. This was with a torch. This was with some other directed heat source. This was such as the spine. This was such as the center portion of double edged blades.