There are some fairly profound differences between smallsword and rapier - though transition weapons by definition closed the gap.
The smallsword family includes some that have a sharp edge, though none are particularly effective at cutting, and is designed (obviously) for thrusting. Duelling foils and similar weapons would fall into this category.
The rapier family is primarily designed for thrusting as well (unless you want to include the sideswords) but has a much heavier blade with two good cutting edges. They produce a greatly wider wound track on a thrust and have the mass to deliver a cut equal to many sabres or even a backsword, in the right hands.
(by way of comparison, my smallswords have 32" blades, my rapier has a much heavier and thicker 37" blade. The differences this creates are significant, though there is much crossover in technique).
Anyway, my feeling is that the rapier and smallsword should be in different categories in terms of wounding (though 1D for a penetrating thrust to the torso is a little light...).