Apple is quite likely able to demand that no other company calls it self "Apple Company" or something like that or has electronics products named "Apple-Something".
However, they have no right to forbid other people from selling Apple Pie or Apple Juice, or selling products in a color they call "apple green", or even calling their company "Johns Apple Orchard".
A trademark is meant to prevent confusion between the products of different companies. Registering "Skyrim" or "Elder Scrolls" as trademarks is perfectly reasonable, as these are important names by which the products of a single company are identified. Which for "Dragonborn" is not the case.
Though remember, that owners of The Elder Scrolls sued other people for using the world "scrolls" in their name, which I cansider nothing but fraudulent.
Edit: Actually, they did it at least twice. At least in the second case, the final result was that the second company can release a game called "Scrolls" under the condition that it's not a direct competitor with The Elder Scrolls series, which as a trading card game/board game hybrid video game obviously is not the case. No likeliness of getting mistaken for each other, no claim to the word.
If Scrolls would be an open world RPG, the situation would probably very different.