Eye of midnight
Even rarer and more valuable than a slime fang, an Eye of Midnight is an ore used to make upper-tier weaponry that is only surpassed by the ultimate weapons for each class. Jet black and shimmering in light, the eye of midnight is definitely a force to be reckoned with when fused with weaponry. It doesn't have any armor applications, because it is solely based for upgrading weapons, and that makes it more valuable due to how effective it actually is.
Other than vague weapon upgrades, not many uses are known for the Eye of Midnight, but it is certain more uses will be discovered as players obtain the item and start experimenting