I've read the Rise of Arsenal issues that are currently out, and the end of Cry for Justice, and I can't seem to figure out where that pesky right arm is. I don't remember any mention of what they did with it, nor did I see anyone sneak the arm off-panel. We may need to get The Riddler one this on to find out where the arm went.
Now, you just don't throw an arm away, do you? Especially an arm of someone who is famous. That's a collectors item. So what did they do with it? Many can speculate it was cryo-genetically frozen, so maybe sometime in the future, they could reattach it. Or maybe it's being used to build some sort of freak super-villain made up of super-heroes ex-body parts. How frightening is that? Franken-Villain? Maybe DC's Frankenstein needed a new right arm. If this was the Marvel universe, I'm sure Terror would have been more than happy to get a hold of that, but in the DC Universe, there's no character like Terror that I can think of.
In all honesty, I have a good idea where that arm will end up at: The Batcave. Although Bruce is out of commission at the moment, that won't stop him from finding said arm and putting it under glass in his museum of crime. Bruce Wayne has made a habit of collecting almost anything he can over his years of fighting crime, even a giant penny. Aside from that, he has tons of old costumes, and other odd collectibles. He has everything there, even tons of Kryptonite. (See Superman Batman: the Search for Kryptonite) What's stopping him, other than death, from getting a hold of that sweet sweet arm and putting it in his bizarre collection, unless someone ate it. (I'm looking at you Killer Croc) What do you guys think happened with Roy's arm? Where did it go?