When forming the construction one of the [plural noun] who (or that) . . . , follow with a plural verb. Thus He is one of the authors who succeed and One of the items that are known is the hammer. A verb, we know, must agree with its subject, and although writers often mistake the subject of this phrase to be the singular one, the subject is the who or that that follows and reflects the plural noun (and leads the clause to which the verb belongs). It’s easiest to understand this logic by rewriting the sentence: Using my first example, rewritten, it would read: Of the authors who succeed, he is one.
Although many writers, both expert and novice, fail to maintain the strict logic of this phrase, the popularity of a mistake does not make it any better—it is still a mistake.