For a long time I avoided executing nobles for fear of the repercussions. But then I saved and tried a few and for me it was the only way to break the stalemate with the Khuzaits. Eventually...it turned into a slight obsession....
....
hmmm...I'm new to these forums as of this afternoon and assumed I could insert screenshots but I guess not?
[imagine here screenshots of the faction encyclopedia screens and all of the Khuzaits and most of the other faction clans are greyed out because they're all dead

]
All in all, my relations with people outside of a few close clans became -100 but after winning so many battles my influence was in the 4 figures so I became generous during castle votes. I was able to work most of the Southern Empire into the positive Influence ranges after a few castle votes.
EDIT.... I'm not sure how the OPs circumstances allowed for him to be swamped because I noticed after the first dozen or so executions that the frequency of running into enemy armies decreased significantly.
Actually, it got to the point where I had to cheat to hunt them down (it really became an obsession at that point). Some nobles stayed in their castles and would not come out or weren't visible as "parties". I had to root them out of their keeps by besieging - cheating to give myself the castle temporarily - yanking them from the dungeon - and then letting the voting take its course because I didn't want the castles just the bodies....
I did this for the Aserai, Battanians, Sturgians, and Vlandians as well. N. and W. Empires are just one person right now lol....
Oh and and there are no minor factions any more...
Finally, peace has been brought to the land

My character's name is Thanos btw