By Ben Marks — A few months back, we received an email from a gentleman named Ian Spellerberg, who lives in Christchurch, New Zealand. “Lovely article about letter openers,” he wrote. “However, what is illustrated is a mix of letter openers and paper-knives. They are quite different.” “Paper-knives are dull by design.” In fact, letter openers and paper-knives represent only half of Spellerberg’s expertise on this arcane corner of old office supplies. As the author of , now available in the United...