A few of the larger Swiss Army knives from Victorinox include a belt cutter. It's a heavy duty, large, serrated, curved knife blade that is sharpened on the concave surface (similar to a pruning blade or a gutting blade, but larger).
The belt cutter is designed for the quickest possible cutting of seat belts or ropes-- for use by parachute jumpers, firemen and emergency workers. The tip of the blade is not sharpened, so you can push it under a seat belt or entangled parachute lines without fear of cutting the attached person! It is also a handy all-around tool for cutting string, ropes, branches, broccoli heads, and just about anything else.
NOTE:-- A blade very similar to this one is included on the retired Safari Hunter knife. It was called a gutting blade, although the modern version of that blade is much shorter.
Uses: To cut with the belt cutter, slip it under the ropes or seat belt, then pull the blade towards yourself while pressing the sharp/serrated part of the blade against whatever you want to cut. If necessary you can saw back and forth, until the cut is completed.