Most single handed swords have a pommel that extends at least a few inches beyond the hand. This is in order to help offset the weight of the blade, but can be used to advantage in techniques like this. In order to execute this you don't need much extra length beyond the hand, just enough to catch a bit of tissue, so even with a pommel that barely extends you can still use grappling techniques. The Kuboton is a great example of this type of leverage with very little actual length.