So here's my attempt at "Nidbanes clearly don't work, what else could we try?"
1/ Players can choose to defend themselves with curses that will be dealt to people who Use combat moves/KO/Murder them. The penalty applied to their attacker scales with the offense committed.
(Not applying this to stealing because theft alts are too convenient)
2/ Curses require some degree of setup/LP investment to start. Can't be too early world or it'd get abused by alts. Can also give players the option to enhance the potency with stat/LP investment like Will/Psy/Lore. Highly invested PvE players being hedgehogs that come at a notable cost to down or murder sounds kind of neat.
3/ The attacking player will be informed in the combat window what types of defensive curses their target has activated (and how powerful they are). Simply aggroing a curse bearer won't activate anything.
One edge case would be griefing the PvE player by locking them in combat but refusing to attack. I'm not convinced this needs addressing since this is already possible and no one does it?
4/ Curse carrying players cannot initiate combat with other players, or take any aggressive combat moves with players as their current target possibly not defend either if the combat system works that way (player+animal aggro being weird?). This is technically the "PvP opt out" PvE players ask for. Applying and removing curses take a long enough time that it can't be used by active pvpers or they'd brick a character for a sudden fight (I'm thinking 24 IRL hours). Possibly other self chosen debuffs to create more potent curses as well.
As much as the "no defending" worked in my head, animals sharing the same openings just makes this too wonky. Not worth modifying the combat system for this idea.
5/ Multiple types of curses to choose from giving the defending PvE player a bit more agency in what they want. Likely handled by the wound system, curses would be magic resistant with no healing boosts of any kind speeding up them going away. But all curses would heal over time.
I'm not convinced this is perfect, but I think this idea of "self limitation for passive defense" is a very useful one. It's very much a desire path for pve types: They want defenses, but they don't want to fight or interact with the combat system. It also gives PvPers choices, you can still ko a guy for his merchant robe but it comes at a cost.
Please feel free to tell me why this is a horrible idea.
Edit:
I never talked about what these curses actually do, and the reality is... I can make suggestions but ultimately the pvpers are the ones who need to honestly suggest things that limit them without being ridiculous. The same pvpers who, by the nature of who we're trying to limit, are the ones actually attacking hermits for entertainment. Catch 22 really.
Suggestions off the top of my head: % stat penalties, things that hurt LP or FEP gain, lower effective quality of gear when worn. None of this stops them from hermit murdering though. All it does is hurt them fighting other pvpers... which many people state effectively stops happening after 1-2 months.
Things that might annoy someone who's purely dedicated to being a hermit murderer would maybe be restricted inventory size? Movement penalty with things lifted overhead? Basically things that make looting inconvenient.