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Regarding the topic, I can say that everything ended with a happy ending. The Dark Messiah, Sareth, killed Arantir, but it's not certain that he lost his body; he might resurrect, although nothing about that is mentioned.
So, is it a happy ending? According to sources, Sareth chose the righteous side of his mother and, with the help of the skull of shadows, closed the rift in Shio, forcing Kha-Beleth to rot there. That's the end of the story of Ashan.
Here, you can read more - http://demilich.by/mm/mm_07.htm
If you're interested in reading about the sixth game, click on the sixth page at the end.