well from the beformentioned color , light and gemstones are all basicaly stormlight .
I always considered that the focus was either strormlight or spren , but your idea of bonds never crossed my mind and it is a very interesting one
and my problem with metal is that unlike form and command which are abstruct concepts loosely related tou the nature of the shard , metal is smt, well that u can touch
i understand what u say but what determines the focus? is it the intencion of the shard ,does it derive from the world as in what whould fit best ,or is it intentional ?