One key feature is its unique plot. It often involves complex assassination missions and the growth of the assassin. Another is the well - developed characters, each with their own motives and backstories. The world - building in the novel is also interesting, creating a vivid setting for the assassin's activities.
The main character is, of course, the assassin. His name and his specific backstory are central to the story. There are also likely to be other important characters such as his targets, his allies who might help him in some missions, and his enemies who are trying to stop him.
It's hard to say without reading it. However, the main character might be a complex figure. They could be someone who was forced into the assassin's life due to certain circumstances, like a tragic past event that led them down this path. Or they could be a character who enjoys the thrill and power that comes with being an assassin.
The main character in this 'world's finest assassin novel' could be a female assassin, which would be a refreshing take. She might use her femininity as a weapon, being underestimated by her targets and then using that to her advantage. Or it could be an older assassin who has seen it all and is nearing the end of his career but has one last big mission to complete. There are so many possibilities without more information about the novel.
The plot might be one of the reasons. It could have a complex and engaging story line that sets it apart. Maybe the characters are well - developed, with the assassin having unique traits and a fascinating backstory.
The unique part is its main character. He is not just a typical assassin. He has his own code of ethics that sets him apart from others in his line of work.
A unique setting can make it stand out. For example, if the assassin operates in a world with a strange magic system or a very different historical period.