Invisible guardian fiend
Mentioned several times throughout the story, the magical luck that pursues Joaquin in his every step is described as his invisible guardian fiend, it would be inappropriate to call it guardian angel given the circumstances. This man, who made enemies with a lot of people and whose vengeful nature inspires fear and cold in many, has incredible luck that contributes to his success, as given from the example of an old friend betraying him and the only Mexican who was a part of Murieta's organization from the given town overhearing the betrayal.
Irony of Joaquin Murieta
Murieta's irony lies in his hopeful youth. He moved to the United States from Mexico in search of a better education and better fortune. He was inspired by his several acquaintances with Americans, whom he had high opinions of, which in turn inspired his admiration towards American people. His hope and his foolish admiration will soon to be crushed, and he will experience cruelty and hatred on his own skin. The story of Joaquin Murieta is, essentially, a story of a man who was disappointed in, and wronged by his fellow men.
Civilized and ignorant
The author doesn't shy away from using irony which shows his own witty character and with which he more effectively emphasizes the messages and intended criticism. The words civilized and ignorant are used ironically, to question the meanings of those words. For instance, he describes Indians as ignorant for having suffered from the hands of the civilized world, indicating that violence is a trait of a "civilized" world. He also describes a "civilized practice" of violent public executions, a sight which he doesn't want to see despite being civilized for many years.
