Hm, I haven't had an issue with executions. I've been doing that since the start, no nobles, nobody to call up armies. Ya people tend to hate me, but I can get my own factions clans to like me by voting heavily in their favor during castle, city and policy votes. You get a way bigger positive boost to the people you vote for, than negative to the people you vote against. I actually headhunt nobles with my army. Recently executed the last army of battania and was immediately given the 4 cities that were under the nobles and kings control. My faction, Aserai, are going to probably take over the continent. We managed to whittle away the largest competitor factions by head hunting and taking castles. Now the southern empire is huge but with limited generals they won't last long.