Here comes the chivalrous. The lawful good under their god or deity. With the power of light they protect themselves and others. The paladin uses white magic to vanish evil, demons, the zombified and the underworld. However, this is not the origin of the archetype. The historical Paladins were Christians. The first idea of Paladins started in Rome in the year 800 followed by King Arthur and the Knights of the round table.
The idea of Paladins (the word originated from Latin and Italy) was to referred those who fought for the king and god (in early Christianity). That these warriors would represent good and be well mannered towards the people and protect them. The word chivalry then became the term that they would use for their educated manners back then as to how they would treat the people and women. They were virtues and if they were to break the rules of the kings court then a Paladin would be thrown out of his rank.
The crusades were consider Paladins since they fought in the name of god. Another name for Paladin is Templar or Inquisitor.
It wasn’t until Dungeons and Dragons was invented that the idea of Paladins involved using magic. After all, the fantasy genre involves things that we have no proof of their existence. We do know that Paladins were suppose to be holy. Followers of god (Dantehs Inferno’s journey to hell). Thus it would make sense that in fantasy, this archetype would posses some white magic abilities. They heal and vanish the undead and darkness.
Now keep in mind that Paladins arent always the sword wielding warriors and use prayer as weapons. Other examples of Paladins would be Van Hellsing. Vanishing the undead.
Watch Curse of the Dragon Slayer and you will see what I mean. Remember that Paladin is just one word. In fantasy this could also fall under Spellblade which are warriors who have magic swords like He-Man or Samurai Jack. Spellblades are commonly used in Final Fantasy.
A good example of the Paladin archetype is Beatrix from Final Fantasy 9.(the picture below)
Magic attacks for this archetype involve using white magic also know as light magic but in my books I call it Illumancy. In Final Fantasy 9, Beatrix vows to protect the queen and princess at all cost and has her own troops.They usually pray to heal much like a white mage (not sure of all that herbal stuff). But over all I would like to use the Final Fantasy tactics video game character design to demonstrate how the ideal paladin would look like.
Originally dresses in white as for all who study white magic. A broadsword (or Sabre if its an Arabian theme). Not sure about the cape but the design is close enough. God I love Final Fantasy.
So again this archetype in many stories you will find them following the orders of the king or queen. Sometimes working for or with a church of some god or deity. Protecting the princess. Praying at a temple. Slaying the undead with a magic sword humming and illuminating with heavenly light.