Punisher

The Punisher is a large cross-shaped gun wielded by the best members of the Eye of Michael, the most commonly seen one belongs to Nicholas D. Wolfwood. There are at least ten in existence.

Wolfwood's Punisher
Wolfwood's Punisher has one machine gun in the front and a rocket launcher in the back. In the anime he has another cross when he first meets Vash, where the side arms of the cross open up to reveal a storage bin for eight Grader 2043 pistols (four on each side), this is before an absence where he returns with the punisher we know. After Wolfwood dies, Vash inherits the weapon, and uses it in his battle with Knives.

in another way

In the manga version, it shows that the side arms are the storage for the machine gun's bullets. Wolfwood uses them in his final battle with Razlo, and he half-destroys the Punisher. Vash puts it on his grave as a cross and move on with Livio; Vash says that he doesn't want to carry Wolfwood's weapon with him because 'It's heavy, it's too heavy". When he says this, it isn't the actual physical weight of the weapon (Vash is known to have demonstrated superhuman strength at times) that is too cumbersome, but rather perhaps the weight of Wolfwood's death that creates its burden on Vash.

It has been noted by many characters that the Punisher is a very heavy weapon. Wolfwood commented on this with, "That's because it's so full of mercy".

Razlo's Punishers
Razlo the Tri-Punisher of Death wielded, as his name suggests, three punishers total. When he was in his Livio state, they were carried by his three henchmen, Agile, Zain, and a third, unnamed henchman.

Chapel the Evergreen's Punisher
Chapel the Evergreen wielded a punisher that splits into two machine guns.

Trivia

 * The Punisher's cross design bears a resemblance to the Centerhead weapon from Gungrave: Overdose, another Nightow work. The Centerhead was wielded by Fangoram (a henchman working for the game's antagonist) and was used in the same way as Wolfwood's.
 * Each Punisher varies in size and shape, but is most commonly 170 cm tall (5'7") and weighs 300 lbs.
 * The "Trigger" in the center of the Punisher is in the shape of a skull.