Zahn believed that magic existed. He even knew, beyond a shadow of a doubt, that leftover relics of magic existed in the world. He owned a few, after all. But he always considered himself a rational sort of guy. When he went on "relic-dives" to uncover lost magic, he did his research.
He didn't believe fanciful myths. He scraped away the garbage and only went after magical items that had a good chance of actually existing. And yet, even though the myths surrounding the powerful Staff of Merlin ...