When you read “leaf blade” right off the bat, you might imagine a blade as thin as a leaf. No, I’m talking about leaf shaped blades. This is a blade that at the hilt is fairly thin, then as you progress towards the point, widens. The climax of the blade width is normally about 2/3rds of the way from the hilt to the point. Once the width reaches the climax, it tapers quickly into the point. Probably the most recognizable example of a leaf-bladed sword is Bilbo’s little sword, Sting.
This blade shape was originally designed by the Greeks, who needed a short sword that they can pull out in the case of the phalanx formation being broken. The Kopis served this very well, but sometimes the Greeks needed something they could stab as well as slash with, something slightly shorter that they wouldn’t risk hitting their buddies with. Something small, but heavy, wide enough and heavy enough for a hard slash, but thin enough to be a stabbing weapon. Thus, they cam up with the idea for a leaf shaped blade, heavy enough at the climax of the width to give hard blows, yet straight and tapered and short enough to give quick, deadly stabs.
The Greeks called their leaf-bladed swords “xiphos“. Classical age Greece was right in the middle of the transversion of bronze to iron, and so both iron Xiphos swords and bronze ones were used, practically side-by side. An interesting fact, is that bronze swords were cast into a mold, whereas iron ones were forged into shape. It took a lot more work to forge iron than to cast bronze, but bronze was more expensive, so they cost around the same, which in turn meant that it was your personal choice.
The sword could be used really however one liked; it was thick enough for hacking but tapered enough for stabbing. It was the ideal secondary weapon. In the chaos that could ensue after the breakup of a phalanx, practically any motion you made could damage the enemy.