I'm sorry if this all comes out as rambling, it goes against several other theories about shardblades, and may be a bit weak, but I'm sort of just building off something I came up with.
*Spoilers follow*
We know from the Well of Ascension plot twist, that Brandon Sanderson likes a good plot twist, especially in relation to corruption, so is it possible we're meant to have one here?
The Knights Radiant wielded shardblades given to them by the heralds (agents of Honor) in the last desolation, but yet Syl (and Honorspren) in referring to Dalinar's forfeited shardblade remarks:
"It just feels wrong to me. I hate it. I'm glad he got rid of it. Makes him a better man"
Now is it just me, or is hate a fairly strong emotion, an emotion that would be more at home with someone affiliated with Odium rather than Honor? Now I understand that Odium provokes hatred from others, so if the Shardblades are of Odium, they would provoke hatred from someone affiliated with honor, like Syl and like Kaladin when he passed up on the blade earlier. But in the alternative could Odium seek to triumph on Roshar by corrupting the now splintered Honor to make the spren of the Knights Radiant 'hate' the shardblades the Knights Radiant so effectively wielded, and separate the Knights Radiant from their weapons.