A pugio is a small dagger used by Roman soldiers. It seems likely that the pugio was an auxiliary weapon that was used only when all else had been lost. It was most likely adopted from the Spanish during the Punic Wars along with the Spanish gladius. The pugio was worn on a Legionary's left, whereas a Centurions wore the pugio on the right.
Like other items of legionary equipment, the dagger was undergoing some changes during the 1st Century AD. Generally, it had a large, leaf-shaped blade 7" to 11" long and 2" or more in width. A raised midrib ran the length of each side, either simply standing out from the face or defined by grooves on either side. The tang was wide and flat initially, and the grip was riveted through it, as well as through the shoulders of the blade.
About 50 AD a rod tang was introduced, and the hilt was no longer riveted through the shoulders of the blade. This in itself caused no great change to the pugio's appearance, but some of these later blades were narrower (under 1 3/4" wide), and/or had little or no waisting, and/or had reduced or vestigial midribs.
Throughout the period the outline of the hilt remained basically the same. It was made with two layers of horn or wood sandwiching the tang, each overlaid with a thin metal plate. Occasionally the hilt was decorated with engraving or inlay. Note that the hilt is 4"-5" long overall and that the grip is quite narrow; it will always seem to be too small.