I recall George Marshall in a pre-dance beginner's workshop explaining giving weight
as something like this:
"that feeling of mutual tension that you use when you are helping someone up off the
floor - you both have to give a bit of pull, or weight, to make it work well. Same with
(not exactly what he said, I'm sure, but that image has stuck with me as very
effective and easily referenced analogy.)
I still haven't heard something really pithy
and direct that will give them the sensation they need to understand.