Gory, grisly and grim can be seen as synonymous on a axis maybe close to brutal. They refer to the appearance. brutal evokes the action that happened. The other words are about how things ended up.

An autopsy can be gory, grisly and depending on circumstances, grim. It is not brutal.

Scary is about a state of mind.

so you have appearance, appearance, appearance, and state-of-mind being considered similar to an action descriptor.