A coup-de-grace change

[Frog Dragon]

You may deliver Coup-De-Grace against a character that is completely unaware of your presence. You may also deliver coup-de-grace with a ranged weapon. Provided you are in standard sneak attack range. You may also deliver Coup-De-Grace to a character you have succesfully grappled, but this requires an attack roll.

That in addition to normal situations where you can use it. I'm generally looking for characters that can sneak good to be able to slash someone's throat open when they're reading in their chair or depict hostage situations mechanically
Does this work?

[BRC]

Congradulations, you just made anybody capable of turning invisible and wielding a scythe an unstoppable juggernaught.
A Coup-De-Grace isn't what somebody does when they sneak up behind a guy and slit their throat, it's what an executioner does when they've got a criminal on the chopping block. A Definite killshot at a range, even if your opponent dosn't know you are there, is nigh-impossible.
Slashing the throat is what Sneak attack does, and at lower levels, it depicts things perfectly. Rogue sneaks up behind a guy with a knife and slashes their throat, guy has an average 4 HP, rogue is dealing an average of 5 damage (1d4 dagger, 1d6 sneak attack). It's at higher levels that things get ridiculous.
I would argue that, for your standard hostage situation, the hostage counts as Helpless for Coup-de-grace purposes, youve got them tied up, with a knife to their throat.

[Spiryt]

Coup de grace when grappled is definetly broken. Others - what BRCommie said.

If you want to do this add some penalties at least.

But while you probably want assasins to be more "realistic", you will instead end with mages who carry scythes with them more deadly.

[Frog Dragon]

I would argue that, for your standard hostage situation, the hostage counts as Helpless for Coup-de-grace purposes, youve got them tied up, with a knife to their throat.

I was fearing somethign like grappler abuse. How about human shield situations?

[BRC]

Just use the Cover Rules. Lets say it's a +6 bonus to AC if both the hostage and the hostage taker are the same size, and the hostage taker is standing directly behind the hostage (Not off to one side).Any attacks made against the hostage taker, if it misses, have a chance to hit the Hostage.

[angus cotton]

You may deliver Coup-De-Grace against a character that is completely unaware of your presence. You may also deliver coup-de-grace with a ranged weapon. Provided you are in standard sneak attack range. You may also deliver Coup-De-Grace to a character you have succesfully grappled, but this requires an attack roll.

I am extremely leery of it. Might want to playtest it a bit first. For example, what would you rule about characters or monsters that are either not flat-footed or keep their dex to AC if caught completely unaware? You know, like a minotaur?

Speaking of Minotaurs, the grapple check/attack roll coup-de-grace might be a bit much since this ruling is heavily slanted in the monsters' favor....specifically large size monsters.

[FoE]

Your proposal might be OK in a Solo campaign, especially if it focuses on an assassin-type character.

[Frog Dragon]

Hmm yeah it does give large size characters/monsters even more of an advantage. Good point. I think I'll just kill this rule