So I have a random theory, I don't think it would have any ramifications on the story if true, but is a fun thought to me. And perhaps someone here will make a connection I haven't seen yet.
While re-reading WoR I was wondering how Lin Davar got the attention of the Ghostbloods in the first place. The Davars are essentially an unimportant family in Jah Keved, as quoted by Shallan at least once. How did Lin convince the Ghostbloods to give him their soulcaster to gain power within Jah Keved? Sure he would be indebted to the Ghostbloods if he rose to the kingship, a very powerful tool for them to have, but they could have done that with any family, why the Davars?
Because they knew Shallan was a budding radiant and a hold on the Davar family would give them an edge on at least one radiant order when they began rising to power.
Shallan's mother figured out what she was and died trying to kill her. This allowed her father to recognize Shallan's powers and use this to gain the attention of the Ghostbloods. I think Mraize was able to connect Shallan with Veil sometime between the mission to get information on Talan and the march onto the plains. This is why he risked going out with the army rather than staying, he knew a Radiant would be his best bet to find the Oathgate.
Kindly ignore that this seems to contradict the theory. i choose to believe that Mraize is underplaying his knowledge so as to keep an edge on Shallan. He states he already guessed at Veil's powers.
I think that this may also be why the Sons of Honor accepted Helaran into their ranks and gave him a shardblade. I have seen a few theories that he may have been bonding a spren himself, but I like this better.
Anyways, what do you think?