One of the upper-tier crafting items for weapons, the slime fang is a very crucial item for expanding the offense and defense of a player. It's value is significantly important to the upgrades specifically pertaining to the Reaper and Beast Tamer classes.
The main importance of the slime fang is its piercing ability for the Beast Tamer class, as when combined with a slime core, it drastically improves the damage output of a whip, at the sacrifice of some speed. It also allows for piercing damage to be done along with blunt damage, depending on how the weapon makes contact with the hostile monster at hand.
For the Reaper classes, multiple slime fangs can be molted and transformed into an incredibly sharp blade that can deal massive damage to the enemy if it happens to score a critical, once again at the sacrifice of some speed because of the nature of how the slime fang has to be balanced.
Other classes often utilize slime fangs as daggers for quick, fast piercing damage at close range, as a last resort. Only Beast Tamers and Reapers can take full advantage of upgrading their primary weapons however, making it extraordinarily valuable to them.
In terms of value with armor, slime fangs can be used to benefit the player's defenses, as well as serving as a cosmetic enhancement of power, as black slides are incredibly dangerous to hunt down and kill.
Other uses for the slime fang have not been made fully clear as they we're drastically changed from the closed beta, but uses will be found as players gain access to them once again.