Yet another theory on what Shardplates might be (Spoilers up to WoR)

[MDA65 she/her]

My theory is that Shardplates are a portion of the Radiants' cognitive aspect, manifesting in the physical realm by a mechanism analogous to that of living Shardblades.

This idea originates because current Plates seem to be sensitive to it's bearers minds: they adapt to the shape of the bearer's body and some experienced ones can even give mental orders to their Plate, for example, causing a part to come off the rest.

We know that the more Radiants progress in their order, the closer they are to their spren. I even think I remember something about their Spiritwebs becoming more intermingled with each step of this process. We also know that spren have the ability to manifest in the physical realm in the form of metal.

Knowing this, it seems possible to me that the Nahel bond may eventually grant the Radiants the ability to bring into the physical realm part of their cognitive aspect, which is shaped around their bodies due to being an extension of the way they view themselves. 

In my opinion, this would explain better than the current theory —Shardplates being minor spren— why Syl doesn't hate those who use current Plates like those who use dead Blades. For in their creation during the Recreance, no spren —not even sub-sentient ones— were harmed, but the very Radiants who broke their oaths were.

[GoWibble he/him]

28 minutes ago, MDA65 said:

In my opinion, this would explain better than the current theory —Shardplates being minor spren— why Syl doesn't hate those who use current Plates like those who use dead Blades.

spoiler for the released Syl interlude:

Spoiler

She describes the Plate that Chord has as having many segments / parts. I think that it is safe to assume that the lesser spren theory is correct

 

[Halyo_Alex he/him]

5 hours ago, GoWibble said:

spoiler for the released Syl interlude:

  Hide contents

She describes the Plate that Chord has as having many segments / parts. I think that it is safe to assume that the lesser spren theory is correct

 

In addition (further spoilers):

Spoiler

she describes the Plate as feeling "content" instead of angry or hateful. Because the lesser spren are happy to be protecting someone, fulfilling their purpose?

 

[Sixth]

I'm going to have to agree with the other two. I believe it is the lesser spren, such as windspren for the Windrunners, that make up the Shardplate. They just have to reach a certain level in their oaths before they have access to it.