I just had an idea while executing my hammerer..
As it is now, grudges are pretty rare.
Now we all know our lever-operated (noble)dwarf execution chambers, be it with retractable spikes or crushing bridges. Or magma
Now wouldn't it be nice to have the game keep track of the 'executioner' , the dwarf who pulled the lever on another dwarf..
And use this to subsequently worsen relations of the deceased dwarf's friends and family with the executioner.
How dramatic this worsening of relations should be I leave open for debate. Personally I'd say if another dwarf killed my mate just once, I'd have some kind of grudge already, yeah
This way, the player has subtle control over developing grudges in the fortress, and the associated fell moods
You could either use the same dwarf for executions over and over again, until he is hated by the entire fortress, by restricting the lever to be pulled only by that dwarf, or allow all dwarves to pull it, creating a more complex web of dislikes among your population.
That is, assuming you make use of execution chambers a lot.
The tracking could prove difficult with magma/ water based execution traps, so it might be best to restrict the tracking to traps, where a lever is linked to the object that directly kills a dwarf.