In most swashbuckling fiction, the heroes engage in heroic antics without the impediment of armor, yet in Dungeons & Dragons (and related games), the only thing (short of magic) that saves an unarmored adventurer from having the worst armor class is a bonus for high dexterity. As a partial remedy for this, I recommend allowing swashbucklers who abstain from wearing armor to take advantage of armor class bonuses for both high dexterity and high charisma (due to audacity). (I believe this option was first suggested in an OSR Web log — I forget which one — in which the subject of unarmored barbarians or Barsoomians arose. I think it is equally relevant to the historical or quasi-historical swashbuckling genre.)
This doesn't completely solve the problem of armor classes in a swashbuckling Old School Renaissance game, but it's a start, and it has the added benefit of increasing the value of charisma.
