(dont have book on me at work so name and exact quote are paraphrased) one line from the the priest guy, to Shallan, about the void bringers became filled with hate (aka Odium). Struck me as similarity to how Ruin could grab koloss, inquisitors, and kandra. the Parshendi seem so diffrent possibly because they were allowed to live outside of Odium's control and without interference from Alethi domestication. If they are aware of this fact they may be eager to avoid being brought under Odiums control again and thier eagerness for Shardblades may have something to do with this. If i wanted to grab the Shardblades from a nation i would absolutly pick a fight with them, and then move to a location where i had a large advantage, in hopes that i could kill and claim some of thier Shardblades.