Lincoln’s Bow
This 19th Century recurve composite bow is fairly obviously enchanted, given that it’s made out of American chestnut while still looking brand-new. Well, brand-new and archaic, at the same time; it’s a hand-tooled, wood-and-sinew affair with about a hundred pounds of draw weight and featuring a single white crystal inset just above the grip. The string was originally gut, but apparently could be ( and was ) replaced safely without breaking the Bow’s enchantment.
And what’s its enchantment? Mostly, the Bow acts as a focus for mystically tracking game. Someone wielding Lincoln’s Bow will soon get a reputation for being a lucky hunter; he or she will just know when and where game will appear. However, this ability only manifests when it comes to hunting meat for the pot. Lincoln’s Bow doesn’t help you track animals for sport, or even for defence; and it will simply never help you track a human. The Bow doesn’t specifically increase damage done with a successful hit, but the fact that use of it negates any defense offered by cover makes it look like that it does extra magical damage, so it’s reasonable that people jump to that conclusion.
Lincoln’s Bow is, of course, in the secret government museum; Abraham Lincoln himself possessed it for many years, keeping it secret for unknown reasons. It’s widely believed that extended exposure to the Bow’s magical precognitive powers awakened Lincoln’s own divinatory abilities, which is one reason why the government keeps it hidden away. Not many politicians are particularly capable of avoiding panic when given an accurate premonition of their own death; even Lincoln himself had to make himself get used to his eventual destiny. And you never know when someone in power might be inclined to meddle.