The very first swords were made of bronze. Since bronze is not as strong as iron or steel, these early swords needed to be shorter than later swords made of iron or steel. However, ancient smiths used a variety of clever designs to maximise the strength and effectiveness of their products.
Sickle sword.
Originally adapted from an ancient farm tool, this design dates back as early as 3,000 BC in the fertile crescent region. The design was very successful and was passed on to Egypt and later cultures of the middle east.
Leaf Sword.
Later bronze age swords from the Hellenic and western European bronze age (~1700 BC-~1000 BC), like this leaf sword, used a design that made the blades thick but narrow near the hilt, with the blade flattening out and becoming thinner before reaching its slender point. This gave the sword a formidably long, pointed, and double edged blade while remaining tolerably strong.
Tapering Sword.
Another method of preserving strength was simply have the blade start off thick, then taper to a point. This method was used in early western swords, as well as this Chinese swords, like this one from during the Han Dynasty (second century BC).
The Roman Spatha.
As smithing techniques advanced, iron and steel were used to make swords sleeker and stronger than bronze swords. During the 1st century AD, the Roman Empire used the Spatha, an advanced, one handed, double edged sword. The Spatha's effectiveness in battle, and Roman's wide influence, means that this sword's basic pattern remained popular for centuries to come (even after the fall of the Roman Empire).