Can a radiant knight be promoted to shard? And if so: what would happen to the spren?

[Onironte Prelan]

Can a radiant knight be promoted to shard? And if so: what would happen to the spren?

[Adamkarma Pahn Kahl]

Any sentient being can become a shard, depending on the spren I guess. Like if a Windrunner were to become Odium's vessel I think that would break the bond and thus killing the honorspren, but if a Lightweaver were to become Ruin's vessel nothing would happen (my guessings)

[jasnah kholin Skaa]

If they were to become a shard it would depend on if becoming one would break their oaths or not, if it doesn't break their oaths then I assume that because they have a bond and share power and sentience to a degree the spren would become something similar to a lesser shard. If becoming a shard would break their oaths then the spren would either die or become something similar to an unmade or twisted spren.