The Pencil of Doom and Mass Destruction is a weapon that was developed by Reich Tech, thanks to future technology given by a mysterious figure known as X. The Pencil is Hitler’s own personal weapon and it can only be used by him. Although the Pencil was supposedly broken by Fegelein, Hitler still has a functional Pencil in 2012, either the Pencil Fegelein broke was just a normal pencil or the Pencil was either fixed or a new one was created. It's effects can cause anything from an epic fail to massive disasters and explosions. It's operation is usually shown as being thrown at a map, presumably at the location of the target on the map. The inspiration for this weapon appears to be a scene in the Original Bunker Scene, where Hitler throws pencils at the map of Berlin after the brief argument with Burgdorf during his rant.
Although the pencil of doom is depicted as a single weapon, Hitler actually throws multiple pencils at the map, as can be seen above.