The Basic ChassisMartial Artists have great DX, and mediocre to low attributes for everything else. They are handicapped in the scouting role by a miserably low Perception and a surprising low ST of 11 limits their effectiveness in combat. They can have some tricks to make up for that.
Their primary skill set includes unarmed and possibly armed combat. They are the only DF template to start with access to Judo and Karate, though the base template isn't very good at either. They have the option of either taking solid (skill-16) levels with two weapons, or increasing their unarmed skills to non-suicidal levels. Their high base DX means they're reasonably good at any DX skill, such as Climbing and Stealth.
Martial Arts also get 7 special, chi-based supernatural skills, including favorites like Parry Missile Weapons, Power Blow, Kiai, and Blind Fighting. Obviously, they're better at the DX based ones, but they have enough of a Talent bonus to make even the IQ based skills semi-viable. Throwing Art is an obvious choice, giving the Martial Artist some minimal ranged capability with slightly better damage. Getting it up to DX+2 (either through investing points from Quirks or by getting more Chi Talent) increases the damage bonus to +2 per die, and a Martial Artist who throws hatchets for 2d+4 cu damage is viable, even on 250 points.
Advantages and DisadvantagesAll Martial Artists have two levels of a Chi Talent, a 15 point talent that usefully effects both IQ and DX based skills, as well as Trained by a Master. Trained by a Master (TBaM) is often seen as the red-headed step child of Weapon Master, in that it is an expensive Unusual Background for accessing Chi skills and improved Rapid Strikes, but doesn't provide any weapon damage bonus. I find TBaM to be a decent advantage, especially if the concept is more "multi-weapon samurai with spear, sword, bow, and fists" and less "Bruce Lee".
Martial Artists get 20 points in discretionary supernatural abilities. Highlights include Damage Resistance 2, Fast Regeneration, Extra Attack 2, Striking Strength 2, and Super Jump 2. The big problem is deciding what to start with out of several good choices, coupled with the realization that there aren't enough points to go around. All templates get better with an extra 50 points, but Martial Artists really don't start to come into their own until 300 or so points (as opposed to say, Knights or Swashbucklers, who were already solidly into their roles at 250 points and are just compounding the nastiness at 300 points).
Martial Artists get another 20 points in general advantages and attribute improvement. There's nothing too surprising here: Combat Reflexes, Enhanced Dodge, Fit, and Weapon Bond all point toward a combat oriented template. Combat Reflexes or another level of Chi Talent are obvious winners.
On the Disadvantage side, Martial Artists have to take Disciplines of Faith: Chi Rituals, and choose from another 40 points with choices that are either Asian Themed (Code of Honor: Bushido) or play up the ascetic disciple concept. There's nothing particularly objectionable. One difficulty is that Vow: Only Fight Unarmed is only worth -15 points, but it's a crippling disadvantage in a world of Acid Monsters and Floating Electric Jellies.
Martial Artist!Martial Artist! is one of the most focused Wildcard skills, covered only unarmed combat, Okinawan and pseudo-Okinawan weapons, and stealth and movement skills in combat. That's not awful, but the Martial Artist ends up spending only 12-24 points on it, meaning they get Martial Artist!-1 or Martial Artist!+0. Wildcards are generally a trade-off between breadth and depth, but it helps to end up skilled enough to do stuff. Weapon using Martial Artists who can scrounge enough points to get Martial Artist!+0 or better should probably take advantage of it; unarmed Martial Artists probably shouldn't bother.
Martial Artists and RaceMartial Artists generally can't afford to be any race other than human, since they only have 20 discretionary advantage points anyway. Desirable and affordable choices include Corpse-Eater, Half-Ogre, Hobgoblin, and Orc (mostly focusing on the more physical aspects of the Chi skills than the straight IQ ones), while Faun isn't terribly efficient but does allow for a high-kicking, head-butting unarmed Martial Artist who can notice things around him. At higher point levels, Minotaurs and Lizard Men bring DR2 to the table and a formidable set of strikers, making unarmed and unarmored Martial Artists somewhat viable. With a lot of available points, Coleopteran and Infernal Martial Artists are options. Coleopteran Martial Artists can have DR 8 without wearing any armor and make excellent grapplers with 4 arms, especially if they also have Gigantism to make it easy to get the grab in the first place.
Equipping Martial ArtistsAs secondary combatants with low strength, Martial Artists want armor, but it needs to be light armor. Choosing the DR advantage from their optional choices helps some here - starting out with effective DR5 (from Medium Leather, a cheap Fortify spell, and tough skin) is not too shabby.
Many Martial Artist weapons are inexpensive, and a lot do crushing damage, so there's no particular value to making them Fine. As such, a Martial Artist should spend the money on Dwarven or Balanced upgrades, helping to offset his relatively low skill.
For ranged weapons, Martial Artists with Throwing Art can pick up whatever random thing they like and throw it, though arrows and shuriken are popular and cheap. Another option is to throw potions and grenades like Alchemists' Fire. A Martial Artist with Throwing Art-18 can nail people with a bottle of Alchemists' Fire for thr+3 damage from a fair distance away, and then set them on fire. It's an expensive trick, but quite amusing. Flash Nageteppos (DF1 p25) are another interesting choice, though not as effective as one would hope. Too many monsters have HT12, and it's embarrassing to miscalculate the distance and blind your allies when Team Monster can still see.
Martial Artists in PlayMartial Artists have a lot of neat abilities, only some of which they can use out of the gate. While the idea of using Striking Strength, Power Blow, and Breaking Blow to hit someone with a kusari for 5d+3 (5) cr damage is amusing, it never happens in practice: neither Team Monster or your own allies are going to stick around long enough for you to spend the 8-16 seconds Concentrating necessary to pull of that trick. Pressure Points has a similar problem, in that the -2 attack penalty minimizes hits, and a Contest of Skills between the Martial Artist's Pressure Points-11 and a typical monster's HT 12 is a losing proposition for the Martial Artist. Parry Missile Weapons, Throwing Art, Breath Control, Kiai, and Light Walk are all more reliable at start. Blind Fighting is a toss-up, being very undependable due to low skill but valuable enough for what it does (you can defend against attacks from behind!) that it's probably worth taking.
In combat, Martial Artists should take advantage of their TBaM ability to make Flurry of Blows cheaply, either to overwhelm the foe's defense or to at least open him up for heavier hitter such as Knight or Barbarian. Unarmed Martial Artists should probably focus on throws and locks, as their most likely damage from karate is a punch doing 1d cr, and no one cares about that. A monster in an arm lock is a monster in trouble, though. Either way, Martial Artists are a light combatant with minimal armor who depend on Retreats and Dodges for defense, so Committed and All-Out Attacks are generally a very bad idea.
Judo tricks bring their own problems. First off, they don't work very well: it's hard to get in a Parry against a monster, have the monster survive for another round, and move into a position in Close Combat the nullifies the monster's shield or other defensive tricks in order to reliably establish a grapple or force a throw. Second, they involve touching the monster with the Martial Artist's bare (or gloved) hands, which opens the Martial Artist to all kinds of nasty auras. It can be frustrating to realize that not only is your character's shtick not very good, it's downright suicidal to even attempt against a Flame Lord (2d bu aura against anyone who touches the Flame Lord in Close Combat). Finally, unarmed attacks can be parried by weapons for damage, and there isn't anything much worse than trying to Arm Lock a Stone Golem and having your hand cut off when he parries with his axe.
Outside of combat, Martial Artists don't do much. They can scout, though not very well, and they're only slightly better in combat than a Thief. Teaming a Thief and Martial Artist up and having them sneak ahead of the party is a bit cruel, but the two of them have a better chance of surviving if the monsters notice them. Martial Artists are also useful for overcoming physical challenges such as chasms in No-Mana zones, which is a rather specialized talent. They're not much worse than anyone else at Meditating, though as usual the Wizard steals a potential niche here, and Meditating for clues is a marginal solution.
In SummaryMartial Artists are really something of an ineffectual class. They can sneak around reasonably well, but with low Perception, they're not good scouts. They have no wilderness lore or monster identification skills. They potentially have some neat combat tricks, but most of them are very slow, very risky, or situational. Armed Martial Artists are less of a danger to themselves, but fare poorly in combination to Knights. All in all, Martial Artists aren't a core member of the delving band, but a 6th or 7th member who might be useful.
One interesting trick is Knight-Martial Artist, either straight or as a samurai build. Knights already have access to lots of weapons, and TBaM works fine for them as less expensive and slightly less effective alternate to Weapon Master. Martial Artist doesn't expand the Knight's out of combat role that much, but every little bit helps.