The weapons that Heine (Mauser C96 and Luger) and Giovanni (Walther P38) use actually reflect their characters and their relationship with each other to a startling degree. The C96 and Luger are very cool guns, but they were both quite impractical: the C96 was big and heavy for a handgun, and it's vicious recoil coupled with a ridiculous rate of fire when set to automatic made it difficult to handle. The Luger is to this day considered one of the most elegant pistols of all time, and even by today's standards, its accuracy is nothing to scoff at, but it was hardly reliable: it required extremely high grade ammunition and even a little bit of dirt would cause it to jam. The P38, on the other hand, is the Boring, but Practical counterpart to these two guns: not nearly as distinctive as the other two guns, but reliable enough that a barely-modified variant was still being used by the Bundeswehr into the 2000s. Like his guns, Heine is showy and impressive, and he does his own thing the way he wants to, but he's also extremely unstable and even he has trouble controlling himself at times. Conversely, Giovanni is more boring: he wears a suit instead of Heine's Impossibly Cool Clothes, he's calm and collected while Heine is Ax-Crazy, and he's very easy for his handlers to control. Furthermore, the Walther P38 replaced the Luger and did its job much more reliably, just like Giovanni replaced Heine in the organization after Heine escaped.
and Luger