I quite liked this last preview. The division between headers in tables is a very common affordance for resizing columns in other apps. On the visual aspect, we could have round corners and a hover style for better presentation, but I know you are still working on it.

You've mentioned the target size of this element, is it possible to have a target size and visual sizes separate? This way we could have something close to 24 units of target size but without a 24 bar or icon? 

For the move handle, what do you think of this icon https://fontawesome.com/v4/icon/arrows or this one https://fontawesome.com/v4/icon/arrows-h ? The bars can convey the notion that there's a menu there.