I looked into dichloromethane as a solvent and plastic welder, it sounded like a nice way to bind the armor components together, but after some of the research, it seems that it's similar to the effects of acetone, but evaporates quicker and builds a bond much faster. But from what I know on acetone on ABS, even though it can weld two piece of plastic together, I'd be opposed to using it as it's simply liquifying the ABS into a bondable state, and re-solidifying; however, it has repurposed the material used for the structural integrity of the piece into a bonding element. Personally, I'd add more material to increase the strength and rigidity of the piece rather than juggling it. I guess since you're out of a good 2 part epoxy resin for joining, this may be a decent substitute. My big fear is how much of the plastic integrity was compromised, only time will tell.
Have you tried sanding/roughing up the pieces when epoxying? Might help the joining process as it gives more surface area to cling to?