In 'a piece of sword' manhwa, the story centers around a character's determination to find the fabled sword. They face numerous obstacles and have to overcome them using their skills and wits. The plot is full of excitement and unexpected twists.
I think 'Solo Leveling' has a great story. The concept of a weak hunter becoming the strongest is very appealing. The story is full of action - packed battles and the protagonist's growth journey is really inspiring. There are also various mysteries and political elements in the manhwa's world that add depth to the overall story.
One similar manhwa could be 'Tower of God'. It has an intricate world - building with different levels and powers, much like 'the sword of the emperor' might have. Another is 'Solo Leveling' which features a protagonist growing in power in a fantasy world. And 'The Beginning After The End' also has elements of a character evolving in a complex, magical setting.
Another theme could be loyalty. Since it's related to the emperor, there might be characters who are loyal to the emperor or the idea of the imperial power symbolized by the sword. There could also be those who oppose it, creating conflict. And perhaps the theme of destiny. The sword might be tied to a certain destiny, either for the empire or for the characters involved with it.
I'd recommend 'The Remarried Empress'. It combines drama, romance, and fantasy elements really well. The chemistry between the leads is palpable and the story has depth. 'See You in My 19th Life' is also good. It has a touching and heartfelt romance that tugs at your heartstrings.