Technically you do that by using "AttachmentNodes". Those are like regular nodes which are transformed to follow a bone (here the palm bone).
I do it with a few intermediary steps, since I use an entity system, however:
That is definitely unintended and a bug I have no clue how this happens since it's not regular lag (it's far too elastic for that). That Idea sounds good (assuming it wouldn't be to hard to make arms elastic), however I don't know if that doesn't make my game too comic-styled^^