Robert,
Be VERY wary of anything which says a pugio blade was 'leaf shaped'. It is a very general term and in my opinion very few known pugio blades would fit the description well.
In fact there are three forms typical enough to be classed into a typology and each of these exhibits a range of precise shapes. These three types are:
Type 'A' - a broad blade whose edges curve to a point and featuring an upstanding midrib.
Type 'B' - a blade shaped similarly to a the blade of a Mainz type sword, with the edges normally narrowing slightly from the shoulders to run more or less parallel for much of the length of the blade. Half to two thirds of the way down the blade the edges turn inwards slightly and run to a reasonable sharp point. Type 'B' blades normally feature sunken midribs created by one to two grooves either side.
Type 'C' blades are shaped like an isosoles triangle and the edges run in a straight line directly from the shoulders to the point. Type 'C' blade generally feature little in the way of an ovbious midrib of any sort.
Obviously there is a lot of variation within these descriptions and some blades are difficult to catagorise into a rigid typology, but I hope that gives you some idea. Your description of blade length is reasonable. It seems that pugiones of different lengths and widths happily co-existed. I am not aware of any developmental trend in size over the course of the 1st century AD, but third century examples are much bigger overall, although it is difficult to draw a direct link between 1st century daggers and the daggers coming from 3rd century contexts. Pugio finds dating to the second century AD are sufficiently thin on the ground that very few inferences can be drawn.
Here is a link to Armamentarium showing a reconstruction of the Velson dagger and sheath. It is a good example of a type 'A' blade.
http://museums.ncl.ac.uk/archive/arma/c ... lsen1a.htm
Here is a link to a picture of a pugio with a large type 'B' blade (which I believe can also be found on the Romanarmy.com imagebase):
http://i17.photobucket.com/albums/b73/C ... gruaro.jpg
Here is a pugio with a very small type 'B' blade:
http://i17.photobucket.com/albums/b73/C ... ndopug.jpg
I don't have any pictures of type 'C' blades in electronic format at this stage I am afraid.
I hope this helps a little.
Crispvs