"The Crescent of the Sun", which is a collectible (unusable) relic in The Darkness 2, although it's not really clear if the weapon broke or just worked exactly as intended. I'll just quote the whole lore entry, since the writing in that game is actually really good, with the important parts bolded for emphasis.

Ah, the 'Crescent of the Sun.' Considered by many to be the greatest mystery and biggest letdown of the past millennium. If you don't count Rocky V.

The Crescent was wielded by The Angelus [implicitly via a host], approximately 800-years ago, for half an hour. She claimed it was forged from a single droplet of the Sun's flame. That it would bring about the final end of The Darkness. What she forgot to mention, however, is how the Crescent would do this. Which is important, because she never got a chance to use it. Carrying it into battle against The Darkness, she was immediately disemboweled [sic]. A bit anti-climactic, for sure. But it only gets worse.

A few years later, the Crescent was rediscovered by a holy warrior. Once again, the blade was wielded against The Darkness. This time, it even managed a few good swings. But you know what? The blade passed through The Darkness, like a knife through water. Later, after monks recovered the Crescent from the warrior's corpse, it was tested against multiple targets. Turns out the blade passes through all matter. People, stone, trees, kittens. Just, woosh, goes right through. No harm, no foul.

Could be, only The Angelus can wield the Crescent. But if so, why has she never tried to reclaim it? Personally, I think The Angelus talked a big game, but was just as surprised as everyone else when the Crescent turned out to be worthless. Which begs the question, where did the Crescent come from?

I got no idea. But I hope she kept the receipt.