Heaven Sword and Dragon Sabre

The third book in the Condor Trilogy by Jin Yong, set a century after the end of The Return of the Condor Heroes.

The story revolves around a pair of priceless and extremely powerful weapons, known respectively as the Heaven Sword and Dragon Saber, which many covet. Either or both of them are thought to allow their wielder to rule the wulin.

The hero, Zhang Wuji, is of mixed heritage: his father, Zhang Cuishan, hails from the reputable Wudang Sect under the master Zhang Sanfeng, while his mother, Yin Susu, is from the unorthodox Heavenly Eagle Cult. As a boy, he lives with them and his godfather, Xie Xun, on the isolated northern island where he was born. He returns to the Chinese mainland and loses his parents after they are cornered on Mount Wudang by several pugilists coveting the Dragon-slaying Saber. At the same time, he is wounded by the Xuanming Elders and survives after seeking medical treatment from Hu Qingniu, a master physician.

His adventures further lead him to discover the long-lost Nine Yang Manual and he masters the inner energy skills within, becoming a formidable fighter. Subsequently, he resolves the conflict between the Ming Cult and the six major orthodox sects, who are intent on destroying the cult. He earns the respect of the cult's members and becomes its leader. He reforms the cult and helps to improve its relations with the other sects. He becomes a key figure in leading the rebel forces to overthrow the Yuan Dynasty.

Tropes exclusive to this book or at least especially prominent in it:

 * Absurdly Sharp Blade: The Heaven Sword and the Dragon Sabre.
 * Badass Grandpa: Zhang Sanfeng, who finished off a would-be assassin with one single hit at the age of 110 and is the most powerful character in the whole book.
 * The Eagle King.
 * Badass Army: The Wu Xing Flags of the Ming Cult in the later chapters.
 * The Casanova: Yang Xiao is implied to be this in his younger days. Zhang Wuji is verging on this in the new edition, when he fantasised about keeping his entire harem of admirers.
 * Childhood Friend Romance: Zhang Wuji and Zhou Zhiruo. And arguably Zhu-er towards Zhang Wuji.
 * Clingy Jealous Girl: Zhou Zhiruo, who later becomes an out-and-out Yandere towards Zhang Wuji.
 * Continuity Nod:
 * The girl in yellow dress who appeared twice in the story is believed to be the descendant of Yang Guo from The Return of the Condor Heroes.
 * The cryptic message that He Zu Dao was asked to deliver to the Shaolin Monk in chapter 2 was actually the location of an important martial art scroll. However, because the message He Zu Dao delivered was wrong, no one was able to understand it. Much later in the story, the main protagonist accidentally found said scroll.
 * Deathbed Confession: Subverted by Yin Susu, who pretended to reveal the whereabouts of Xie Xun and the Dragon Sabre to a Shaolin Monk as a Thanatos Gambit to screw over her enemies.
 * Deep Cover Agent:
 * Fan Yao,
 * tried to be this. It took Yang Xiao about 5 seconds to realise she's a spy.
 * Driven to Suicide: Zhang Cuishan and Yin Susu.
 * Face Heel Turn: Song QingShu because Love Makes You Evil
 * Forgot I Could Change the Rules: How the members of the Ming Cult forced Wuji to become their leader -- the Ming Cult was under the second wave of attacks from the orthodox sects and could only escape to the the forbidden passage if the cult leader changed the rule.
 * He Who Fights Monsters: Cheng Kun deliberately provoked Xie Xun into this as part of his Evil Plan.
 * Honey Trap: Despite her Lawful Stupid facade, this is Nun Miejue's modus operandi against the Ming Cult. She tried to get Ji Xiaofu to do this to Yang Xiao and Zhao Zhiruo to Wuji.
 * Improbable Age: a little sleuthing reveals that all of the Ming Cult leaders (except the Eagle King) were in their early twenties when Yang Dingtian, Wuji's predecessor, died.
 * Last Girl Wins: Zhao Min was the very last girl Wuji met out of his harem of admirers.
 * Lawful Stupid: The most sympathetic reading of Nun Miejue.
 * Loads and Loads of Characters: Even by Jin Yong's standard, Heaven Sword and Dragon Sabre has an absurd number of characters. This point is driven home in the 1999 TVB adaptation, when the Ming Cult's Five Men Band is cut to Three in order to save costs.
 * Love Dodecahedron: Wuji and his harem of admirers plus Song Qingshu and Zhou Zhiruo.
 * MacGuffin:
 * The Dragon Sabre, leading to many MacGuffin Melee.
 * Strangely averted with The Heaven Sword, which no one cared about despite being as valuable as The Dragon Sabre.
 * May-December Romance: Yang BuHui and Yin LiTing
 * Meaningful Name: Yang Buhui which literally means no regret.
 * Mighty Roar: Xie Xun's Lion Roar drove everyone on Wang Pan Shan into madness.
 * Not the Fall That Kills You: A common Jin Yong's trope. Wuji not only survived his cliff jump but gained an ancient Wuxi text that cured his internal injuries and gave him awesome wushu skill.
 * Rape Is Love: A very fitting example is Yang Xiao and Ji Xiaofu. It's supposed to be justified and okay because, well, secretly she wanted it.
 * Second Love: Wuji's first (and arguably strongest) love being Zhiruo. It takes her completely screwing it up for him to eventually decide to go with Zhao Min.
 * Star-Crossed Lovers: Zhang Wuji and Zhao Min with Zhang Wuji being the figurehead of the Ming Cult which was revolting against the Yuan dynasty government whom Zhao Min was part of, being a princess and all.
 * Tangled Family Tree: Ji Xiaofu, Yang Xiao, Yang Buhui and Yin Liting. Ji Xiaofu was engaged to Yin Liting when she was raped by Yang Xiao and subsequently had Yang Buhui. 18 years later, Yang Buhui fell in love with Yin Liting largely because she pitied him for losing Ji Xiaofu to her father. No wonder even Yang Xiao was speechless when Wuji broke the news.
 * The Empire: The Yuan dynasty.
 * Time Skip: A huge leap. We jumped from a teenaged Zhang Sanfeng to his 90th birthday between chapter 2 and 3.
 * And then some as the protagonist, Zhang Wuji grows up.
 * Took a Level In Badass: Zhou Zhiruo