What is the specific usage of the English adjective into the form of of plus noun?

What is the specific usage of the English adjective into the form of of plus noun?

This is the so-called noun in front of the addition of an adjective (can also be used as a predicative and attributive, x0d as an attributive, often after the modified noun. For example: an issue of importance), The tolerance of water loss is of obvious advantage in the desert. Materials shall be of sufficient thickness Advantage is equivalent to advantageous and so on, \All side effects are of gastrointestinal nature. All the side effects are of gastrointestinal nature. The symptoms were of mild nature. Believe it or not, For example, in the second sentence, Malignant tumors can be classified into several types He is of royal blood. He is of royal blood. He is not of royal blood These boilers are of low-pressure design. These products are of high quality. These products are of pensionable age. He is old enough to get a pension Marriage today is less of an ego trip and more of an economic barrier for men, \"Marriage is an ego trip." this is not entirely true because marriage is not the whole of life