Why do the Shards grant the powers they do?

[Ampere]

After reading all the books about how the shards get their specific investiture. I don't see how lashing is of honor or how steelpushing is of preservation. Do all the shards have the same powers and they just choose the investiture or it somehow looked them personally? Was Ati like I thing metals dope so I'm gonna have people swallow it if they want to use investiture? 

[Inky]

They don't create the powers at all. Magic systems simply come about when a Shard Invests on a planet- this unavoidable. The planets sorta choose the powers, is what it seems like. What the Intent does have influence on is the method of using these powers. Surgebinding comes from bonds (Honor), Allomancy gives you extra power so you preserve your own (Preservation), and so on. 

Edited June 22, 2019 by Inky

[Weltall]

These WoBs may help:

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Chaos

Allomancy provides many very dramatic effects, which some have noted is not very much like Preservation. Could you walk me through how Allomancy is of Preservation, though it does dramatic, dynamic things?

Brandon Sanderson

One of the 'basics' of the magic in all of the worlds is that the energy of Shards can fuel all kinds of interactions, not just interactions based on their personality/role. I did this because otherwise, the Magics would all be extremely limited.

The 'role' of the Shard has to do with the WAY the magic is obtained, not what it can do. So, in Preservation's case, the magic is a gift--allowing a person to preserve their own strength, and rely upon the strength granted by the magic. While Hemalurgy has a huge cost, ending in net entropy.

/r/fantasy AMA 2011 (Aug. 31, 2011)

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Questioner

From what I understand, Ruin and Preservation create the world together, and they created humanity as copies of the original humankind. So how did they give Allomancy to Scadrial?

Brandon Sanderson

Yes. So the magic systems are kind of built into the setting and the world. And there are certain natural pathways that exist, in the same way there are certain natural pathways for them to create life. Which is my explanation for why life is so similar on all the different planets, is that they're following natural pathways, and these magics are kind of the same way. For instance, Lightweaving predates the Shattering of Adonalsium. A lot of these other things are suggestive of magics that existed before that were built around Adonalsium. They weren't 100% created by the Shards, but they also do have the Shards' influence on them.

Skyward San Diego signing (Nov. 7, 2018)

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The powers of Ruin and Preservation are Shards of Adonalsium, pieces of the power of creation itself. Allomancy, Hemalurgy, Feruchemy are manifestations of this power in mortal form, the ability to touch the powers of creation and use them. These metallic powers are how people's physical forms interpret the use of the Shard, though it's not the only possible way they could be interpreted or used. It's what the genetics and Realmatic interactions of Scadrial allow for, and has to do with the Spiritual, the Cognitive, and the Physical Realms.

Hero of Ages Q&A - Time Waster's Guide (Oct. 15, 2008)