I wouldn't say that this exact phrase is a well-worn cliche, but the format is well known. I've also heard 'Long on style, short on substance', as well as other variations.
The meaning of each of these types of statements is to compare traits of a larger subject, especially when one trait is vastly overrepresented compared to the other, "Long on [trait A], short on [trait B]." (This is also true if one trait is vastly under-represented.)
Neither is a common phrase, but we can make a good guess from context.
By implication, cracking his thumb (I'm guessing in the same sense as "cracking your fingers") is an insulting gesture in the speaker's culture.
"Black be its fall" is an idiomatic version of "may its fall be black", and again by implication is intended as a wish that the House of Shaws shall fall in an unpleasant manner.
You didn't tell us where this came from, but I'm guessing (from the use of "laird") that this is intended to be a Scots dialect or something related to it. If you want to research the exact meaning of these phrases, that may help you do so.
(@FumbleFingers' guess that these may have been made up is a good one. It was common for authors to invent "bad language" -- curse words and the like -- to avoid printing something that might offend the reader. We still see this in television scripts, such as the invention of "frack" in Battlestar Galactica. It's also common when you want something that seems appropriate for the speaker's culture but aren't willing or able to do the research to find the correct phrase -- lazy, but common.)
Best Answer
That's either a sarcastic comment, or a paradox or an absurdity.
If you read it in reference to orbiting a planet, it's a paradox. If you fall, gravity will always bring you to the ground. Some say that orbiting is falling (because you are subject to the Earth's gravitational field), but not hitting the ground, because velocity keeps you from doing so.
Some pilots like to joke that flying is easy; what's hard is learning how to miss the ground. It's kind of an absurdity. It's reducing the very complex to a simple untruth.
So one of Douglas Adams' characters (Arthur Dent) manages to learn to fly by falling and missing the ground. (Life, the Universe and Everything, book 3 of 5 in Hitchhiker's Guide to the Galaxy)
If it was said sarcastically, it can mean a stupefying degree of ineptness:
"He can't do anything. He could fall and miss the ground."
Conversely, it could indicate a great success from what was surely considered by most to be a failing:
He fell and missed the ground. (It looked bad but he ended soaring to great heights.)