Punisher

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

Wolfwood's Punisher
The Punisher has two machine guns in front and a rocket launcher in the back. In the anime, the side arms of the cross open up to reveal a storage bin for eight Grader 2043 pistols(four on each side). After Wolfwood dies, Vash inherits the weapon, and uses it in his battle with Knives.

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 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.