No matter how clearly laid out you think your tenets are, there will always be ambiguity and oathbreaking will always seem arbitrary. In the "old days" of D&D there wouldn't have been any question as to whether or not killing goblins was "good". No paladin would lose his god's favour for killing them, irrespective of who attacked first. I am very sure that you couldn't come up with a list for any of the gods that wasn't plagued by subjective interpretation.
Oh yes, I agree there are going to be limitations. Not so much because I think oathbreaking is subjective, but because intention matters, as do all sorts of other factors that it’s unreasonable to expect the game to accommodate.
I’m glad Larian have attempted the oathbreaking system, but without a human DM (or, as per that other active thread, a very good AI!) it’s never going to be close to perfect.
But I do think there are some obvious candidates for reassessment, eg killing slavers and goblins who are clearly preying on travellers for oath of devotion, that if changed would reduce frustration. And for the grey areas, when I said I want the option to argue whether I agree the oath was broken, I don’t expect the game to let me explain my reasoning let alone have the sophistication to assess whether my rationale is good. (So perhaps I should have said “indicate” rather than “argue”.)
It could just give me a pop-up after the “oathbreaking” action that lets me say whether or not I agree the action is against my oath, or an additional dialogue option with the oathbreaker knight. And I don’t care that some players might abuse that system and say they have a justification for their action when they don’t. Though I’d be okay with still having to pay the fine and be told to reflect carefully on my actions, even if I disagreed I’d broken my oath, to discourage too much of that. Or even to need to pass a persuasion check with the oathbreaker knight to avoid a fine. The important thing for me is to be able to register my view. (I do think it would be feasible to do more than that, eg to generate some standard defences for different action types, and to distinguish actions that are always going to break an oath vs ones about which there could be some argument), but for me that would be a nice-to-have rather than a must-have.
I feel forewarning of oathbreaking would undermine my roleplay, and steamroller over ambiguity in a way I think I’d find frustrating. Eg, say I’m playing a devotion paladin who would execute a murderous goblin to protect innocent travellers, but get some sort of message that says “this action breaks your oath, are you sure you want to proceed?”. I’d still disagree it actually broke my oath, but now I either need to decide not to kill the goblin after all (which would be contra the roleplaying decision I’d made for my character) or would need to go ahead anyway and do what I think is in line with the oath. Doing the former would be really unsatisfying for me, whereas the latter leaves me no better off than now, and possibly worse as I don’t even now have the “excuse” that I didn’t think the action broke my oath.
I suppose an acceptable middle ground would be to prompt before the “oathbreaking” but give the option at that point to say that I disagreed the action broke my oath and would go on and do it anyway. Given whether the game thinks an action is against my oath is irrelevant to my decision-making, personally I’d find that needlessly intrusive and flow-breaking, but if other folk would act differently if they knew how the game was programmed to view the action then I’d see it as a fair compromise.
(And of course none of this addresses actions that are against oaths but the game doesn’t recognise as such, which was a bigger problem for me in my playthrough than accidental oathbreaking!)
