I would have to say an AGI build is quite important for this. 18-21 at least, maybe even 8 athletics, and no armor over 12 weight. Stick to 8-12
I am a shielder but I practice swashbuckling on duel server for fun and to improve my manual blocking (which isn't very good since I use shield all the time), and my 24-15 build just sucks for it. Decent duelists with greatswords and even longer dueling polearms just dance outside of my range. With a shield I can just put it down and bullrush them and then maintain position so lower athletics doesn't hurt me, but without it I have to play that dancing game too which I inevitebly lose with a much shorter range weapon and lower athletics.
I would think a long weapon like long espada would be useful too, so would making use of that stab. You'd also need to be really good at holds, footwork and headshots to make up for low damage of only 6 PS.