So you're mainly worried about someone with a water breathing talent putting in a massive amount of effort into griefing people... killing them, dragging their bodies for who knows how long, while starving and getting dehydrated, risking their own lives to permadeath from predators... just to be an ass?

I dunno man. Seems like you're bending over backwards to conjure a hypothetical scenario of someone out there in the world looking to permadeath people. In almost all cases they won't perma-die any way. Once you spirit walk back to near your body, you appear in the nearby area... like the top of the ocean for instance. This is all apart of story telling any way. A mass murderer with a talent to match isn't impossible to avoid. In these scenarios you're making you're always the victim. It's not impossible to crossbow these guys between the eyes when they try it.

Obviously fireballs are a potentially lethal talent. But you could do this all day.. trying to figure out what could be exploited to cost people money... only to find out that using these powers costs them their own Soul, plus the massive cost for killing someone.

Moving people against their will doesn't really happen in this game.

You can't detain and drag people away unless you have a bounty token and are "heading in the direction of jail". (Even this mechanic, in my opinion, is probably going to get scrapped or revised but that's a different topic)

Spirit walking has been described as primarily an aesthetic for the experience of near death. It requires no skill and you can't fail it unless you choose to do something besides walk in a line. There's never been any evidence to suggest that other players can prevent this from happening -- probably because it would be complete bullshit if they could.

I was under the impression that spirit walking would be timed based on your remaining spirit, and the cord connecting you to your body would be brighter or fainter based on your character's age. So you would be able to fail, resulting in permadeath.

there's a talent called spirit walking, think astral projecting. i assumed it was for helping out those that are dead to find their body quicker.