Swordsmen

Swordsmen, also known as Wu Xia, is a 2011 film directed by Peter Chan and starring Donnie Yen and Takeshi Kaneshiro.

Liu Jinxi (Donnie Yen) is just a non-notable villager in a small village, but he was able to kill a pair of bandits, one of whom was a very skilled fighter and on the most-wanted list. Detective Xu Baijiu (Takeshi Kaneshiro) is sent to investigate.

Thus begins a martial arts thriller that asks touches on themes of law versus good and destiny versus free will.

Tropes used in Swordsmen include:

Setting, Plot, and Themes

Emotions Versus Stoicism: Detective Xu Baijiu falls squarely on the Stoicism side, and he cites his past experiences as a justification. He has even used acupuncture to suppress the emotion of caring and mercy for others when it conflicts with upholding the law. The events of the film challenge this belief.
Heroic Sacrifice: The detective gives his life to turn the The Master into a lightning rod. It's worth it.
Love At First Sight: How the Lu Jinxi and his wife first met.
Sliding Scale of Free Will Versus Fate: A theme debated through the events of the film. For Lu Jinxi, it is whether his past will haunt and perhaps kill him, either by his former gang or by the law, or whether he can successfully make a new life for himself. For Xu Baijiu, it is how much people choose to be evil and must be held back by law or how much circumstances may conspire to result in evil. These two characters actually sit down once and have a chat about destiny.
To Be Lawful or Good: The Moral Dilemma that Xu Baijiu faces, as he gradually realizes Lu Jinxi truly has reformed himself.
Wuxia: The setting--with small rural tribes and secret martial artists--is effectively this, even though the detective's western clothing is unusual for the genre, and the film is technically set in the early 20th century.

Characterization

Badass Normal: How do you expect a mere detective and coroner with knowledge of physiology and acupuncture to aid in a fight against an extremely skilled martial arts master? Well, he could try some acupuncture needles. And then he could try some more needles. And get killed in the process...but actually help them win.
Crouching Moron, Hidden Badass: Considering that a random paper mill worker named Lu Jinxi killed a skilled fighter and bandit who was on the most-wanted list, the detective deduces that Jinxi is not what he seems.
Good Is Not Nice: Xu Baijiu once released a juvenile offender to foster care, thinking said offender had reformed. The offender proceeded to poison his foster parents and almost Baijiu himself. Since then, he has resolved to not let people off the hook of the law easy, and to keep any instinct of mercy or kindness out of his work.
Heel Face Turn: Lu Jinxi, from his being a cold-blooded killer many years ago, as the Number Two member of the 72 Demons. And later, the detective becomes this, as he changes from being an antagonist to Lu Jinxi to a friend and ally.
Lawful Anal / Knight Templar: The detective, especially to Lu Jinxi. The Xu Baijiu explicitly states that law is the only source of true justice in the world, but Lu Jinxi has been trying to establish a new life free from his former crimes, through his personal repentance.
Old Master: The Don cannot be hurt by the impact of blades and can throw people clear across the room. This old man is extremely dangerous. He's practically a Lightning Bruiser, exhibiting excellent offense, defense, and speed.
The Don: The Master of the "72 Demons" gang of assassins.

Metacontext

Exactly What It Says on the Tin: The movie has a Wuxia setting, as indicated by the Chinese title of the film. Averted, however, with the English title, since the film has relatively few swordsmen.
Spiritual Successor: Director Peter Chan cited the 1967 movie One Armed Swordsman as a major inspiration, and he and Donnie Yen decided to indirectly reference that movie in this one.
Whole-Plot Reference: largely a remake of A History of Violence.