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human
CMV: The Reality Stone was badly used in Thor: The Dark World

Major spoilers for Thor: The Dark World (obviously; aka Thor 2), Doctor Strange, and Avengers: Infinity War (aka Infinity War)

Minor spoilers for Captain America: The First Avenger, Avengers, and Guardians of the Galaxy.

In Thor 2, Malekith attempted to use the Aether/Reality Stone to extinguish all light in the universe forever. The Reality Stone was the right one for the job, in my opinion, since that would require rewriting reality to have no light.

However, that implies that Malekith was powerful enough to wield an Infinity Stone and knows what it is capable of, but all we see him use it for is dust storms, levitation, and tendrils. He was facing the prince of Asgard, who can use lightning and Mjölnir. Sure, Malekith had an Infinity Stone, but if he doesn't use it in battle, he would be just as vulnerable as without it.

Malekith never used Aether-specific powers, i.e. reality rewriting powers. Contrast with the other Infinity Stones. The Tesseract (the Space Stone) was used in Avengers to open portals (for Loki and the Chitauri on two separate occasions), and as we found out in Infinity War, to transport the Red Skull to guard the Soul Stone. (Hydra could be excused for not understanding its power.) The Mind Stone was used to mind control Hawkeye. The Power Stone can be used to destroy entire planets. The Time Stone was used to rewind time, speed up time, and save and reload.

This is an even biger problem once we see Thanos using the Reality Stone *by itself* to set up illusions, turn people into blocks or strings, and turn knives and energy blasts into bubbles. Even if Malekith wasn't the trickster type, he could have utilized the Reality Stone's other abilities, like turning Mjölnir into bubbles, or making a butterfly stab Thor.

I really want to like this movie. Christopher Eccleston was in it and he did a great job as the Doctor, but I just can't like it if the Reality Stone was used so badly.

TL;DR Malekith has Reality Stone, uses no reality powers.

EDIT: What would bring me closer to changing my view is evidence that the Infinity Gauntlet allows for greater control over the Infinity Stones (without using the Reality Stone as the example, obviously).
gpt
Malekith was also using a raw Infinity Stone. Compare that to Thanos, who had the gauntlet, which allowed him much finer control over the use of the stone. This seems to be the purpose of almost every stone-powered artifact. It heavily limits the stone's power (the time stone when contained in the Eye could be overpowered by the normal human villains of Dr Strange), in exchange for giving a lot more control. Even the Gauntlet did this, since Thanos wasn't able to make any permanent alterations to reality, which Mantis and Drax returning to life after he left despite how beneficial it would've been to him to kill them.

In short, it makes sense that Malekith wouldn't be able to use the same powers Thanos did, but he got the benefit of being able to impact the entire universe with only one stone instead of needing all of them.