Personally, I always took it as an example of the Pathetic Fallacy, an anthropomorphization of nature. Caradhras isn't sentient, but it is a mighty mountain, tall and hard to cross, with nasty weather and dangerous trails. The "cruel" moniker that Gimli gives the mountain seems like the sort of thing that people who frequently suffer from the weather and hardship would say.

Personally, I always took it as an example of the Pathetic Fallacy, an anthropomorphization of nature. Caradhras isn't sentient, but it is a mighty mountain, tall and hard to cross, with nasty weather and dangerous trails. The "cruel" moniker that Gimli gives the mountain seems like the sort of thing that people who frequently suffer from the weather and hardship would say.