A falchion is a medieval single handed, one edged sword of European origin. Falchions are found in different forms from around the 11th century up to and including the 16th century. In some versions the falchion looks rather like the scramasax and later the sabre, and in some versions the form is irregular or machete like. While some propose that encounters with the Islamic shamshir inspired its creation, these "scimitars" of Persia were not developed until long after the falchion. More likely it was developed from farmer's and butcher's knives in the manner of the larger messer.

The blade designs of falchions varied wildly across the continent and through the ages. They almost always included a single edge with a slight curve on the blade towards the point on the end; they also were affixed with a quillioned crossguard for the hilt in the manner of the contemporary long-swords. While one of the few surviving falchions is shaped very much like a large meat cleaver, or large bladed machete (the Conyers falchion) the majority of the depictions in art reflect a design similar to that of the grosse messer. A surviving example from England's 13th century was just under two pounds in weight. Of its 37.5 inches in length, 31.5 are the straight blade which bears a flare-clipped tip similar to the much later kilij of Turkey. It is worth noting that this blade may have been influenced by the turko-mongol sabers that had reached the borders of Europe by the 13th century.

Unlike the double edged swords of Europe, few actual swords of this type have survived to the present day; less than a dozen specimens are currently known. It is presumed that these swords had a lower average quality and status than the longer, more expensive swords. It is also possible that falchions were used as tools when they were not pressed into service as weapons.