In fantasy literature/games, a paladin is basically a "Holy Knight". They are warriors who have divinely-granted powers, whether you call it "cleric magic" or "white magic" or whatever else. In some settings, they can also heal with the laying-on of hands (this derives from D&D, where they have that exact ability). D&D also sets the archetype of paladins always being Lawful Good - to reflect the fact that the historical inspirations for them were knights who lived by strict codes of honor. Which few historical knights actually did; the paladin is the archetypical Knight In Shining Armor.
The origin of the term is indeed from the excerpt that the above poster quoted from something, but that term applied only to a single group of knights. The inspiration for fantasy paladins draws from a wider selection, ranging from Charlemagne to Arthurian legend (the Knights of the Round Table, of course) to the Crusaders to who knows what else. St. George and Joan of Arc would probably qualify, as well as various other notable individuals, historical or legendary, throughout the Middle Ages. (For some reason, people associate the concept of the paladin with the Christian faith and western knights, although I am sure there are similar exemplars worldwide.)
In Guild Wars 2, we have five races of varying faiths, including one atheistic one. The term "paladin" carries inherent religious connotations - therefore, we call them Guardians. Their code: to mend and defend.
Purple lipstick and weeaboo on paladins? Nevermind the clunky and impractical armor, the whole thing looks beyond stupid.
PSN: Valkod Playing Dark Souls and Baldur's Gate Trilogy right now.