Wikipedia describes a falchion as “a one-handed sword” but by core rules a falchion is a two-handed weapon. Wikipedia goes on to describe it as “a single-edged sword, whose design is reminiscent of the scimitar. It combines the weight and power of an axe with the versatility of a sword.”
Weapons Chart Entry
Pathfinder RPG Core Rulebook. Copyright 2009, Paizo Publishing, LLC; Author: Jason Bulmahn, based on material by Jonathan Tweet, Monte Cook, and Skip Williams.