Even though it won't be very effective against enemies that are immune to Poison, it can do plenty of damage to enemies that aren't. Still, because it is poison damage, remember that it does damage over time. Blacktongue is not an appropriate sword to use when surrounded by hordes of opponents, since it would take 6 whole seconds in order to deal out the maximum damage it can. Additionally, if an enemy has reduced poison duration, then it would not suffer the whole damage given.
Blacktongue also prevents Monster Heal. This is particularly useful in later difficulties such as Hell Difficulty, when Monster Heal can be an incredible pain. However, whether or not Blacktongue's damage is still effective in later difficulties, and whether or not its targets are immune to poison, may limit its usage.
One-Hand Damage: (10-11) To (28-30)
Two-Hand Damage: (30-32) To (42-44)
Required Level: 26
Required Strength: 62
Sword Class - Normal Attack Speed
+50-60% Enhanced Damage
+113 Poison Damage Over 6 Seconds
Prevent Monster Heal
+50 To Attack Rating
Poison Resist +50%