A hyporbole is being used
hope this helps
Dialogue and verbs that draw a reader into the story
The adjective “grotesque” typically refers to something that is repulsive or ugly.
The adjective “barbaric” refers to something harsh and unrefined.
To glow with “barbaric lustre” means that they have an aggressive and uncultured appeal.
There you go!
The answer someone has already given isn’t right. the reason this sentence is personification is because promises are not people they cannot physically give someone a key.