Guys, I figured out a fix for the limp weiner arms.
Just stick a small, tightly rolled piece of toilet paper (so that it looks like a tiny piece of rope) between the arm peg and the slot where the arm peg slides in on the figure. The piece of toilet paper basically reduces the size of the slot, creating a tight, snug fit for the arm peg. As a result, the arm fastens in place nice and tightly and it won't go limp. Play around with the thickness of the rope becuase if it's too thin, it won't work. I had to use two layers of toilet paper to get the right thickness.
Sadly though, I did discover another shortcoming while sliding the arms in using the toilet paper. The articulating joints on the arms are super weak and will basically go bad after just a little bit of use. Some of the articulating joints click in to place when you articulate them, but the plastic is so cheap that it stops clicking in to place after just a little bit of use, and will quickly stop working altogether. One of my points of articulation is pretty much already dead.