The value of a watch has a lot to do with its quality. Chances are that your engraved watch was a high-quality piece. People rarely engrave junk. If your watch was made by an important company like Rolex, Omega, Carrera, Patek, or another similar brand, it will be valuable.
Many watch collectors do not want engraved pieces, although there are some that do. Some collectors enjoy the sentimental value. Others may like to research the owner for a bit of history. If the name is famous or historically significant, that can add great value, providing it is authentic.
An old book is not valuable just because it is old. There are many variables in the old book business. Value can be determined by condition, writer, the importance of the book, rarity, and demand. If the name in the book is the writer's autograph, that will increase its value.
If the name is "Aunt Betty" or something, the book's value is diminished, especially if the writing or bookplate is on the title page. A name on a blank page will not devalue the book as much.