In Heart of Ember, the main character Ember and her best friend Nico use many unique phrases, insults, and unusual slang. These were actual phrases that were commonly used in the Victorian era. Several books from the Victorian era document the phrases and insults, including the Dictionary of the Vulgar Tongue.
Another book dedicated to documenting the once colorful phrases and insults is Passing English of the Victorian Era, by British writer James Redding Ware, published in 1909.
Ember uses a few terms from other eras, including a Roman expression, Dolorum Ipsum, along with Victorian phrases. Interestingly, Graphic Designers often use Lorum Ipsum as a shortened version of the words as a placeholder for forthcoming verbiage.
Some of these phrases have contemporary and recognizable variations still in use today. Ninnyhammer becoming Ninny.
While other phrases have had something of a renaissance in popular culture, Skullduggery being popular with pirates, for example.
Sometimes the meanings are pretty obvious.