In play, swashbucklers are very combat focused. They deal a lot of damage with their attacks, especially against foes that have vulnerable parts, but they also have good defenses against most attacks. Their big weakness in combat is their generally low DR, which makes them vulnerable to aura and area attacks. Out of combat, the base template doesn't have many ways to contribute, but since all swashbucklers have Luck, they can always try something and hope.
The Basic ChassisSwashbucklers have high DX, moderate HT, and low ST and IQ. They have a high Basic Speed and Move. All this nicely suits their role as fast, mobile melee combatant, though most swashbucklers are going to want more ST (or at least more Striking ST, but generally more ST).
Advantages and DisadvantagesAll swashbucklers get a very effective starting package of advantages: Combat Reflexes, Enhanced Parry, Luck, and Weapon Master. These, combined with their high weapon skill with fencing weapons, means that swashbucklers have very solid Parries, even against repeated attacks. The mandatory Luck provides protection against enemy critical hits and friendly critical misses. The lack of High Pain Threshold is a bit of a weakness for a primary combatant, but most swashbucklers don't expect to get hit in a fight.
On the disadvantage side, swashbucklers are not required to have Overconfidence and Impulsive, but almost every player takes them. The rest of the disadvantages are a mix of Codes of Honor, dubiously sane Vows, and various mental issues that reinforce the concept of the swashbuckler as a rake, a rogue, and a party animal.
One of the great strengths of the swashbuckler template is 60 points in optional advantages. Obvious choices from the template include more ST and DX, Extra Attack, and Ambidexterity (a lot of swashbucklers fight Florentine-style with two rapiers). Extra Luck is another good choice. Rapier Wit is also an option, but most swashbucklers don't have a high enough Public Speaking to reliably make use of it. The only possibly mandatory advantage is 2 points in total of extra ST or Striking ST, so as to get an effective ST of 13 for damage purposes and an extra +2 damage for swung weapons.
Expanding the Swashbuckler with a LensAnother option for the swashbuckler is to spend 50 of those optional advantage points on a lens, which can expand the swashbuckler's combat or non-combat options. I think that swashbucklers lensing into thieves make for more enjoyable thieves than the straight Thief template, as well as giving the swashbuckler interesting things to do out of combat. The various spell-casting lenses aren't particularly potent, but a low skill spellcaster can do stuff out of combat. Swashbuckler-Bard is an obvious combination, especially for people who want to play a more charismatic, seductive swashbuckler.
The various combat templates are less satisfactory. Swashbuckler-Scout solves the issue of the swashbuckler not having good ranged combat options, but is also involves careful juggling of weapons to decide whether to engage with the bow or the sword. Swashbuckler-Martial Artist ends up spending a lot of points on the mostly redundant Weapon Master/Trained by a Master combination, and there are easier ways for a swashbuckler to learn Power Blow.
Swashbucklers and RaceA third option for some of those advantage points is to add a racial template. Cat-Folk is an obvious choice, providing a bunch of benefits such as Night Vision 5 and DX+1 at the low price of 25 points (since both swashbucklers and Cat-Folk have Combat Reflexes, swashbucklers get a 15 point reduction on the price of the Cat-Folk template). Coleopteran is another great, if expensive, choice: the innate DR is higher than most swashbucklers get through gear, the lack of armor means more weight can be devoted to weapons or gear without providing encumbrance penalties, and multiple arms means that a coleopteran swashbucker can carry two edged-rapiers and a shield while still have a hand free to hold a crossbow or main-gauche. Gargoyle is an unorthodox choice, but flight is always a good ability for melee types. Most races make good, or at least decent, swashbucklers.
Leprechauns and pixies make for less optimum swashbucklers, as those races many advantages don't make up for the massive reduction in damage that their sizes impose. It's not impossible, but there are generally better options - even if a swashbuckling pixie has numerous literary antecedents. Minotaurs are another bad choice for swashbuckers: swashbucklers depend on their parries and dodges for defense, and don't have the HP and DR necessary to survive while going berserk.
SkillsEvery swashbuckler has at least skill-18 in at least one fencing weapon: usually Saber or Rapier, and possibly higher depending on how important the swashbuckler thinks a shield is. Two weapon swashbucklers are really popular, since it maximizes the Weapon Master and Enhanced Parry advantages, but I think that swashbucklers are generally better served by learning how to use a shield and having a defense against arrows. For ranged weapons, swashbucklers get thrown knives, which are horrible. There's almost no point in using them.
Swashbucklers also get Jumping, Acrobatics, and Stealth, making them good escorts for a thief or scout who is scouting ahead for the delving band. They have the usual choices for background skills, including First Aid, Carousing, and Hiking. With their attributes, swashbucklers should focus on DX based background skills, not the IQ choices.
Swashbuckler Skills or Swashbuckler!For most templates, the choice of going with the Wildcard skill over a rash of skills is easy: the Wildcard gives a higher average skill level for almost all secondary and background skills and only a slightly lower level for primary skills. And if the game is using the Destiny Point rules from PU5: Impulse Buys, it's an even easier choice. Swashbucklers are the exception: giving up 3-5 levels of their sword skill in exchange for slightly better levels of skill at Acrobatics is probably not an advantage for a template so focused on a single weapon.
Equipping SwashbucklersAlthough most of the sample swashbucklers in SJ Games sources use small-swords or non-edged rapiers, the true munchkin shells out the big dollars for the edged-rapier: the combination of impaling or cutting damage, flexible reach 1 or 2, and fencing parries is well worth the base cost of $900. The hard decision is whether to buy one or two of the things, and whether to buy a cheap one to start out. The savings for a cheap sword are impressive, and the risk of breakage is pretty low, but a swashbuckler has a lot of advantages and skills tied to their sword, and having them break is painful. It's also generally not affordable to add many qualities to the starting sword: a Balanced, Fine Rapier costs $9000(!), which is 18 points of Signature Gear - which is 18 points that could be better spent elsewhere.
Swashbucklers are generally not particularly strong and are penalized by encumbrance. Other than their weapons, they want to carry as little weight as possible. They generally can't afford the weight of the heavier armors, leaving them in DR2 Heavy Leather (or DR3 Fortified and Lightened Heavy Leather for games with inexpensive enchanted items) at best. There's a temptation to not wear armor and rely on their blades and speed for defense, but I believe that any DR is better than no DR, even if it's just a suit of Light Leather.
Swashbucklers in PlaySwashbucklers are murderous in combat, especially against the usual range of starting foes in DF. Against typical orcs and ogres, a swashbuckler can Rapid Strike and reasonably expect to get a hit in every turn, and usually do enough damage between Weapon Master and targeted attacks to the vitals to take out the target. They can be less effective against constructs and spirits, but those are usually boss monsters in beginning DF play. By the time that creatures with high DR and good skills are common foes, most swashbucklers have improved swords and skills and can still contribute.
Outside of combat, swashbucklers have less to do. They lack even the weapon identification skills of knights, and don't have enough Perception to scout reliably by themselves. They make acceptable escorts for Thieves or Scouts who are scouting ahead, and depending on the lens chosen (if any), they can pick up a lot of out-of-combat utility.