Brackish blade

The Brackish blade is a one-handed weapon that requires 60 attack to wield. It is dropped by 'Rum'-pumped crabs in the combat dungeon unlocked in the quest A Clockwork Syringe. It has a higher stab bonus than Korasi's sword, albeit a lower strength bonus. Unlike other popular stabbing weapons such as the Zamorakian spear and Korasi's sword, the Brackish blade has an aggressive stab stance, which is useful for those who do not wish to gain Defence experience. This weapon is equal in all stats to a Dragon scimitar, however the stab and slash are switched. Because Korasi's sword and Chaotic weapons are harder to obtain and have higher requirements to equip, this weapon is of great use to players fighting monsters weak to stab, such as dragons. Since it is not a spear though, its damage is cut in half when fighting the Corporeal Beast. Many players on the forums will sell this sword at a price around 2 million coins.

This weapon does not need the quest to be completed to be used.

The weapon, along with the Brine sabre, also seems to do more damage against the rum drunk crabs, as the player receives a message in the chatbox that "The brackish blade seems super-effective." This is likely a reference to Pokémon.

Special attack
The Brackish blade has a special attack,  ' Rum'ify. It doubles the chance of hitting, and adds 2.5% of the damage dealt to your Strength, Attack and Defence, draining 75% of the special attack meter. If the target is low on health and the hit is fatal, even with low damage, the player's stats will still be boosted according to what the hit would have been. As this special attack visibly boosts stats, it of course does not stack with the effects of any potions or any other boosts.

Trivia

 * There is currently a glitch which allows players with under 60 Attack to wield the blade using a Super Attack potion.
 * The special attack is probably a spoof on the brine sabre's special attack, liquify. They have the same animation,and the only difference is that liquify can only be used underwater.