Mercwerx makes a really nice push knife a seraphym, and cold steel's safe keeper II may be better suited to all around use single edged and not quite as long. A push knife does not have to have a "T" handle, rather it is merely a short bladed knife that is easily and quickly and easily accessable.
A great all around short blade is the schrade/baer desigend Sharpfinger. Relatively cheap, 25 dollars or so, with a upswept blade for more cutting power, it is hard to wrong with one.
Try the Scharde forum in the manufacturing section of Bladeforums if you want to read about them.