I have to correct one thing, Confused. Brandon has stated fairly unambiguously that the Shard's Mandate (I think he used intent in the WoB, but I like the Mandate term too) only really affects how you gain access to the magic, not what it can do. My view from the WoB's I've seen plus in-world clues is that the Shard provides the method of Initiation, and in some cases provides a way to lose the power (ala Surgebinding), but the world and its foci in particular affect how to actually use the magic (metals on Scadrial, colors on Sel, etc) are an unconscious interaction between the Shard and the planet itself, and the Shard's Mandate doesn't play a role in what is possible with the magic system at all.
jW