Fate and the Will of Heaven
There are a number of potential tools in the GM section regarding this. There is also the Fated Flaw, which characters can take. The Fated Flaw and the Fated tools available to the GM are part of the same underlying set of procedures and advice. The flaw simply brings them into focus on a single character in the party.
The Fated Flaw has a number of accompanying tables. The GM rolls secretly on them and this establishes a fate for the character. This could be a number of things as the table is about three tiers deep. It could be anything from "to become vengeful and evil" to "be loved by your worst enemies" to "cause harm when trying to cause good". Keep in mind these are not outcomes, they are more like a force of gravity the character carries. She can deny her destiny, rebel against it, while it is the job of the GM to occasionally introduce encounters, situations, events, etc that reinforce heaven's will.
In addition, characters can acquire Fate through misdeeds. When someone does something exceptionally terrible there is a percentage chance that they gain the Fated Flaw. In this instance, the fate would be created by the GM to fit the act itself.
These are both exceptional circumstances. However there is also a more general approach to fate that applies to the entire party using similar methods. In addition there are suggestions for something called The Fated Encounter.
The will of heaven is a real thing in the setting, discussed in the GM chapter. This matters for things like Emperors staying in power but also for developments that personally intersect with the player characters (particularly at the more advanced end of the game). We have a section in the GM Chapter called "Truths of the Setting" which makes details like who holds the mandate of heaven and why clear. It also gets clarifies details about deities and the cosmology.
Luck and Good Fortune
Luck and Good Fortune also matter in the setting. The calendar is arranged so that each month is associated with certain things. For example the Month of the Monkey Moon is considered an auspicious time for taking risks but an unlucky time for making important political or financial decisions. More involved attempts at divination can determine if particular days are auspicious or inauspicious for a given task. Doing things on inauspicious days can result in bad luck, which imposes penalties and undesirable events. Doing things on auspicious days can make for more favorable conditions and give the characters bonuses in pursuit of their goal.
I've talked about this a lot on the blog and it is one of the key parts of the game. Grudges arise in play when characters make enemies (usually by killing people). When they acquire a grudge (whether it be with an individual or a sect) that goes onto the Grudge Table. The Grudge Table is a living Encounter Table that keeps growing as the game progresses. You don't roll on the Grudge Encounter Table all the time though, only when it comes up as a result on the regular Encounter Tables (presently about 2% of the time).
There are rules for maiming in the game, and there are techniques to make maiming easier. There are also mechanics for overcoming the disadvantages maiming imposes, allowing for Blind Swordsman and One-Armed heroes. There are even special techniques available only to characters who are maimed in a particular way.
Kung Fu Techniques
The heart the game of course is the system of Kung Fu Techniques. These use a mechanic similar to Sertori powers in Sertorius: each technique is tied to a skill, and rolling the skill performs the technique. You can use techniques as much as you want, but performing them at full strength can imbalance your Qi energy.
Counters are a type of Technique that are important. Using counters you can block, dodge and counter-attack your opponents when they strike (and they can do the same to you).
There are different ways to categorize the martial arts abilities in wuxia. We chose to group them into four disciplines: Waijia (External Kung Fu), Qinggong (Lightness Kung Fu), Neigong (Internal Kung Fu) and Diaxue (Pressure-point Kung Fu). Characters start with innate talent in these, being ranked 0-3 in each. The greater your rank, the better you are at those techniques.
This is the internal energy that heroes in the system can cultivate to perform profound feats of Kung Fu. It makes them physically stronger and allows them to do such things as heal, create energy blasts and attack with blinding speed.
You advance by defeating opponents who are more powerful than yourself, and as you advance you can learn new techniques. One way to acquire new Kung Fu techniques is through manuals. These are an excellent tool for building adventures as gaining them often involves exploring dungeons or breaking into a sect's temple.
Sects and The Martial World
Primarily we tried to embed the genre in the setting (which is one reason why encounter tables play such a big role in the game). The personalities and martial sects that populate the setting are a big part of this. Wuxia features funding sect and colorful characters. The players may or may not belong to a sect, but they will likely encounter the forces of their politics.
I may be overlooking some elements here (my brain is mush today) but these are the basic features of the game meant to reflect the wuxia genre.