Don't drop 2 handed items out of your backpack with only 1 free hand.

[valtsu0]

Currently, if you try to take a 2 handed item from your back (or anywhere else) you will drop it onto the ground. Instead you should be unable to move it.
I do admit this is mostly a skill issue, but i can't say i have ever wanted to do that. Instead, i have accidentally dropped tasers and nukie weapons quite a lot of times.