Smallsword is another weapon that I have an interest learning more about, but for different reasons than any other weapon I have studied. Longswords, broadswords, and rapiers were developed as highly refined killing tools for their situations. In contrast, smallswords seem to have been defined by fashion and society rather than lethality. Why people would trust their lives with a weapon that is just not as effective as a rapier is something worth learning more about. Here is a neat website that talks about the systems: https://smallswordproject.com/.
UPDATE 5/19/19 – I have done some light sparing with a smallsword recently and while it does seem to compromise lethality for convenience and fashion, it isn’t as bad as I thought. The speed and agility of the weapon are real advantages and I could see fencing a rapier with one provided I was careful with measure.
Also of note, Castile has come out with an economy smallsword at $189! https://castillearmory.com/product/complete-economy-small-sword/