The original Arsenal was a pretty much nobody and midget whose real name not revealed at all, perhaps too insignificant for the story and in-story at worst. Coupled with self-hatred for his own small stature, he grew into an antisocial criminal with little to no respect and dignity who turned to the life of crime partly to take his anger to the world.
If there's something that kept him from being a true nobody, that would be his keen inventive mind that allowed him to built a powered suit with a wide variety of weapons. Dubbing himself Arsenal, he hired himself out as a paid assassin.
He first came to public attention when the unscrupulous Nicholas Galtry hired him to slay Garfield Logan, the teen hero known as Beast Boy, a frequent ally of the Doom Patrol. Galtry was the teen's legal guardian and had been embezzling Logan's inherited fortune for some time, even as he horribly mistreated the youth.
In the end, Arsenal I was defeated by the members of the Doom Patrol and arrested. His armored suit was taken into custody, but later stolen by Galtry, who used it himself for another try at Logan. The original Arsenal remains in prison at this writing.
Multitude of firearms and bladed weapons
Nicholas Galtry was the legal guardian of Garfield Logan following the death of Logan's parents. An unscrupulous man, Galtry sought to acquire Logan's inheritance, and donned the armor of Arsenal in order to bring his plans to fruition.
The Arsenal is a man in a menacing green robotic suit with a sword that shoots lightning and has machine guns for hands. He also has a shield, jet boots, breathes fire, and shoots lasers from his eyes. He appears in "The Last Patrol" trying to kill Robotman and the rest of the Doom Patrol.