PVP Rules: Keeping PvP Fun
PvP should not always end in PK. Many times just beating someone once and leaving a solid threat that next time they die should be enough. If you just wanted to steal something, just subdue them and steal it. If you want to convert someone to your god, it may take more than just "Convert or Die" why not actually try to convert them first with words, by defeating them a few times to show your strength, or through a series of challenges to prove your god/philosophy is better–then if none of that works call out "convert or die". It'll be much more fun for all involved, and who knows who may wind up having their faith shaken during the roleplay that follows. Plus if you're enemies know you're loathe to kill, they will be slow to retaliate with death themselves. -Keep in mind, mechanics are a part of the game. Simply because someone has more potions than you doesn't mean you can toss fear out the window, supplies and equipment reflect the skill and experience of the warrior, after all. It's why you never see level 20 fighters in anything less than +3 full plate and weaponry. Superior equipment is a mark of experience and power, after all.
If you do decide to PK, at least try to give the other player a chance to escape and they should be aware you intend to kill them (give suspicious glances, draw weapons and threaten them, don't simply leap out of invisibility to "win" a fight). Its not fair to attack someone on FD when you know they're on SD and that the worst that might happen if your attack fails is that they SD you and leave you there then flee. They should know you planned to PK them at least so they can decide if they desire to return the favor.
If you engage in PvP and leave some Near Death, or kill them but don't full loot. Its polite to make sure that wandering monsters don't finish off the poor Near Death guy. Its alright, even preferred despite the OOCness, make sure any near by monsters are dead and gone.
Remember, PvP is a question of mechanics. If you engage in PvP, understand these mechanics. Realize people can transition faster than you, and may escape that way. Realize subdued characters remain subdued a certain length of time, after which they can get up to fight or drink potions. Realize there is no way to properly enforce a "disguise", and there is no way for a player to enforce permadeath or even lengthy deaths (Although, the DMs do have a process for adjudicating situations where this comes up between players who can not agree between themselves).
If you want to do anything outside the normal mechanics of NWN in PvP, you must get a DM to help with it. That DM should know what you want to have happen well enough in advance to be able to help too. This isn't an excuse to ignore someone has subdued your character and is emoting "put a sword point to Joe's throat" and jump up simply because the mechanical time limit wore out on subdual. I mean, he did subdue you and did put a sword to your throat.