Crocodile's Hook

As Sir Crocodile has apparently lost his left hand in an unknown incident before his introduction, he has a giant gold hook in place. It has a giant base at the place where it connects to his arm, and the hook itself is curved sharply.

Abilities
The hook is made of a tough gold-alloy, which makes it very difficult to break, the alloy is strong enough to block a hit from the sword of the world's strongest swordsman Juracule Mihawk. It is also very sharp, and can easily pierce through a person. Being gold, it is also resistant to corrosion.

The golden part is actually hollow, and can be taken off to reveal a secondary hook. This one has a metallic gray color, and has pores all over it. It contains a very concentrated scorpion venom that can dissolve rocks at a mere touch, and paralyzes the afflicted victims until they die of cardiac arrest. The poison is so strong, that it releases a slight purple poisonous mist and liquid through the pores. Nico Robin held a bottle of antidote to the poison. This hook is less durable than the golden one, as when Monkey D. Luffy smashed it against the ground, it snapped clean off.

Should the hook be broken off, Crocodile can somehow reveal a switchblade from the broken tip of the base.

Crocodile usually uses the hook in conjuncture with his Suna Suna no Mi powers to extend the weapon's attack range.

Trivia

 * Crocodile's hook is a reference to pirates who lost their hand at battle. The stereotypical replacement would be a hook in many fictional stories, although such limb replacement was not unheard of in real world piracy as loosing limbs in battle was a constant danger.
 * In a Cover Story Mini-Arc, Crocodile was once shown to have both hands, and no hook. This was corrected for the release of the volume and is now published with the hook correctly placed on his left arm.
 * In episode 117 of the anime (roughly at timing 18:06), Crocodile can also be seen lighting his cigar with both hands, and no hook.
 * During his incarceration in both a regular prison and Impel Down, Crocodile was permitted to keep his hook, despite it being a potential weapon, lending credence to the assumption that the hook is a prosthesis rather than a bizarre gauntlet.