The way I figure it, the ending where you kill yourself with the Immortal Blade is your character reaching oblivion (the truth death). Either TTO dies with you thereby destroying your him, your soul, which would be oblivion pretty much, or killing yourself forces TTO to rejoin you at the last moment so that you can pass the Eternal Boundary. You see TNO and he looks like he's hanging his head in shame, Deionarra standing behind him. I wonder if it's a sign of him failing his quest, or if it's actually a good ending and he's spending eternity with Deionarra.
That was the one thing I wished had been about the ending. It didn't wrap things up with Deionarra very well. There was a sort of tragic aspect to her ending. Seeing as the incarnation she knew was really cold and had no compassion, but she seemed to see something in him. And he basically just used her right up until the end, then let her die just to play a small role in a plan which would benefit himself. Then she keeps saying you'll be reunited in death, but during the main ending your character walks off to spend eternity in the bloodwar or something. I thought the perfect ending would have been for your character to join Deionarra in death, the next life, whatever you call it. There are so many interesting messages and hidden themes to this game. The fact that you and Pharod really had similar destinies, both trying to cheat fates caused by previous crimes and injustices. Morte too, telling a lie which led to the death of another "you", and in turn he journeys with you and guides you, in a way repaying his debt. I guess PS kind of has that underlying karmic theme.
I remember something that might be important from BG2. There's one merchant in the Adverturers Mart who is selling a few PS character items, like Dakkon's sword and that sort of thing. And it stated as the item descriptions "Soandso was killed while serving a creature known as the nameless one" for each of them. Could that mean the proper ending is one where your characters die in the fortress? Then again if that stuff was written by different people it wouldn't really be counted, but maybe I'm just overthinking things with that one. Anyway there are only a few games that have actually moved me, FF7 and now Planescape. Truly I don't care much for Interplay at this point, scrapping two great sequels and then Black Isle itself. I can't pretend to know all the facts but it's a real shame. I almost feel like not playing any more Rpgs, it's like all the great things about Rpgs are pushed to their utmost limit in Planescape and there's nothing more to see. Hopefully I'll shake that feeling off though heh