he Longsword evolved in Europe during the medieval period as a response to the development of heavier armour. It first appeared around 1250, achieving popularity in the 14th century. It remained in common use until 1550 where after it became something of a ‘sports’ fencing weapon till it disappeared sometime in the 17th century.

he blade is straight and double edged at least 36 “ long although it can get as long as 42”. Early period blades have groove(s) down the centre (called fullers) designed to lighten the blade without weakening it. Later blades have a diamond cross section (or other thickening) to give extra rigidity for dealing with heavier armour. The hilt was large at 12”+ (much larger than needed for a single handed sword) since both hands were required (most of the time) for effective use. Pommels could be a variety of sizes and shapes with discs popular in earlier weapons but ‘scent stopper’ pommels

becoming preferred in later ones. Crosspieces varied considerably although they did tend to get larger in the later period.

Longsword was normally used in both hands with techniques for using the point, edge, pommel and even crosspiece to strike the opponent. In early period Longswords, the edges were parallel and the sword’s point was a somewhat secondary offensive feature. At this time the sword was mostly used to hew or chop. As armour improved in protection, the chopping Longsword evolved into the thrusting B@stard sword. This was a weapon (so called as it was neither a single handed nor a true two handed sword) with an elongated isosceles triangular, rigid blade relying on the point. Using the sword in a sort of bayonet drill (left hand on the blade, right on the hilt) was popular in fully armoured combat. This allows the wielder to thrust, block or strike with the pommel with considerable power.

More details about history can be found here