I don't know if this was proposed before, however I would very much like the ability to show both weapons on my character, whether it looks like a train wreck or actually quite cool. Especially when a character is equipped with different types of two-handed weapons, to say a Big Giant Hammer(TM) and a Blunderbuss, the positions of these different types are actually nice enough to look good.
So I believe it could be an option, defaulted to turned off, and I believe many players would like to have this ability to show off a little.