I saw this suggestion on the subreddit and thought it to be simple and seemingly effective.
Allowing the Assassin to Frenzy kill once per game will prevent D1 Prince claims and kill the Prince claim meta single-handedly. The Enforcer can keep his own Frenzy ability or be replaced with something else. Maybe he can take the 2 for 1 ability? Sounds OP.
If you DON’T like this idea -
Make it so the King’s Execution pierces healing so Evil Kings can’t fail on killing the Prince and be outed the next morning. This would also make Princes hesitant to claim.
If you DON’T like THIS idea -
Feel free to give your own that doesn’t involve whispering.