Swords can be found with several different edge geometries, each with its own strengths and weaknesses.

When it comes to Chinese swords, few, if indeed any, have survived in original polish. By this, I mean the edge geometry the blade had when it first left the smith. Some years ago, I asked Philip Tom, a sword polisher with decades of experience restoring period Chinese swords, whether he had ever encountered one in original polish. His answer was no.

The only early blade I have encountered that appears to be in original polish dates to the period of the first emperor of the Ming dynasty. Obviously, a single example is not enough to draw conclusions.

Below is a brief overview of the edge geometries most commonly encountered on swords.

Full Flat Grind

This edge geometry is found only on modern swords. It is the easiest grind to produce and is well suited to modern grinding equipment, which is why many contemporary forges favor flat-sided blades. A full flat grind creates an extremely sharp edge by keeping the blade thin behind the edge. This “razor”-like profile allows for clean slicing with minimal resistance.

The trade-off is durability. This geometry does not support heavy impacts or rough targets particularly well, though tougher modern steels help offset this weakness. In test cutting, a flat grind produces smooth draw-cuts and excellent soft-target performance, but the edge is more vulnerable when striking hardened bamboo or, historically speaking, bone, armor, or during hard blade-on-blade contact.

For beginners cutting light targets, this geometry works well, as it bites easily into the target and compensates for minor edge misalignment.

Back-Heavy Cutting Convex

Historically, this appears to have been the most common edge geometry used on Chinese swords. More material is retained toward the spine, giving the cross section the familiar “apple seed” shape. While not as sharp as a flat grind, this geometry still cuts effectively while offering greater strength and durability against harder targets and repeated striking. This likely explains its prevalence on period Chinese blades.

The added material near the spine also supports proper blade-flat deflections. In addition, this shape tends to push material being cut away from the spine, reducing friction when cutting denser targets and improving overall efficiency. Swords with a back-heavy convex geometry are an excellent choice for those seeking historical accuracy in their sword work, particularly in test cutting.

Front-Heavy Cutting Convex

I have not encountered this edge geometry on Chinese swords. In this configuration, more mass is shifted toward the cutting edge itself, making it the most robust edge among the various geometries discussed here. While this produces a very strong edge, it also results in a comparatively dull cutting surface.

Rather than employing this type of edge geometry on sword blades, Chinese martial culture appears to have favored blunt striking weapons for battlefield use when greater durability and impact resistance were required.

Center-Heavy Cutting Convex

In this geometry, the convexity is distributed through the middle of the blade, creating a balance between sharpness, durability, and smooth penetration, while still maintaining support behind the cut. This form likely results from a blade that originally had a back-heavy convex cross section and was repeatedly re-polished through use. As the edge is re-sharpened, often in the field, the thinner edge section is gradually reduced. Over time, this narrows the blade and transforms the cross section into a more continuous curve.

While some sharpness is lost, a blade with this geometry retains the robust strength needed for a soldier in the field. It also maintains the reduced-friction cutting efficiency described above. As such, it can be considered a solid “general purpose” geometry, one that does not excel at extremes but performs reliably in deflection and holds up well against hard targets.

It should be noted that blades with this type of edge may struggle with very soft targets, such as the plastic bottles commonly used in modern cutting practice. They would, however, be entirely capable of cutting down a tree.

Closing Summary

No single edge geometry is universally “best.” Each represents a balance between sharpness, durability, cutting efficiency, and structural strength. Historical Chinese swords overwhelmingly favored convex geometries that retained material behind the edge, prioritizing reliability, repeated use, and performance against harder targets over extreme sharpness.

Modern flat grinds excel in controlled cutting of light targets but trade away durability. Front-heavy convex edges maximize strength at the cost of cutting ability and were historically addressed through the use of blunt weapons rather than sword blades. Center-heavy convex edges reflect the realities of long-term use and maintenance, evolving naturally from repeated re-sharpening in the field.

Understanding these geometries helps practitioners make informed choices, whether the goal is historical accuracy, training efficiency, or practical performance.