I've always found it weird that there are only 9 Unmade.
I know Brandon mentioned that the 9 unmade that were similar to the orders of knights and the Bond smith was the exception. Could there be a reason for this? My theory so far has been that since, the bond smiths bond with three "god" spren the Stormfather, the Nightwatcher, and the "Sibling". And the stormfather is of Honor, the nightwatcher of Cultivation, than the sibling must be of Odium. Could the bondsmith be the replacement of the Unmade?
This bondsmith wouldn't necessarily be evil, but we've seen through Maleta that the KnightRadiants aren't all good and righteous. The bondsmith would see the other side of the conflict, this could explain some of the conflict within the Knights.
Is my theory reasonable? Do you guys have any better theories for this? If I'm right, who could the sibling be?