Ghostly flaming apparition of a blade, slayer of spectres and all that is ethereal, wielded by its durable hilt inlaid in gold, silver, ivory and white pearls. It can turn the tide when fighting the intangible.
Real World: some Indians in the Amazon treat their eyes with a traditional potion applied with palm leaves. Brutally painful, the drug alters vision, giving the jungle's dense green walls greater texture and dimension. You could adapt this to desert or swamps, or other hard to navigate regions.