These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Katrina: "I bet you say that to every girl who chains you up and has a whip."
Game Breaker: The Paladin class as a whole. In Quest for Glory III, once the Paladin earns the "Heal" ability he's granted the Magic skill. By Quest for Glory V the Paladin can learn every spell in the series, except for the handful of that specifically require being the Wizard class to learn (most of which are plot-specific). The Paladin is therefore not only a hybrid Fighter/Wizard, but he also carries the best sword in the game, and has his own class abilities on top of that!
Fan Nickname: Often thought to be averted, since the name of the main character is known, among many fans, as Devon Aidendale, a name taken from a strategy guide. Word of God says it was just the name of that writer's character and insisted that the hero is supposed to be whoever you want them to be.
What Could Have Been: The Coles have said on record that several intended features had to be cut from the series for various reasons, usually time and technical limitations. For example, the first game was supposed to have different races (Gnome thief, Elf wizard, Centaur archer, Human jack-of-all-trades) and a large Goblin warren maze; the former was replaced with the three classes, while the Goblin base remains as The Artifact of the latter. Similarly, the fifth game lost the ability to use bow and arrow, and to play as Elsa, over the course of its development.
Other artifacts of the first game: The workshop appeared to be occupied in the original version of the first game (the remake made it more clear that it serves no purpose); it, along with the butcher shop, barber shop, and bakery were probably intended to serve some sort of purpose that was scrapped, and thus are always closed in the final version.
Word of God: The series was originally intended to be four games, but in the design process for Shadows of Darkness the Coles decided that going from an evil wizard to an Eldritch Abomination was too far a jump for the Big Bad, and made Wages of War as a transition. In a 2008 interview, they added that after completing Trial by Fire, they felt that Rakeesh and Uhura were "crying out to have their stories told".
Additionally, the Coles have said that Glorianna, the games' setting, is an alternate Earth which suffered an explosion of magic, creating the various animaloid races like Liontaurs, as well as making time flow differently in different parts of the world (hence the Schizo Tech).