First of all im a horrible person,
So i would love a way to knock out people, allowing you to handcuff them and throw them, stripped of their euipment, in a cell and let them rot or force them to do manual labour,
of course to make this vaiable persons would either have to RP a fear of death (unlikely) or some gameplay mechanic should punish you for dying because with your euipment gone, that would be the only fear of dying and players would just provoke you shooting them.
Avoiding the Slavery you could just capture an important person (the master engineer who is unimaginly skilled in coming up with designs) or someone who has some skill (there where skills, right?) incredibly high, making them valuable.
(please let me be the evil slaver foundation making trips to undefended core worlds taking slaves and be the most hated/wanted player in the universe)