The past events are not changed to mean something completely different. We are just learning more about how those events came to be. The Nathrezim delivered the helm and blade to the Legion who turned it into the end result that we saw on Azeroth. Learning more with an expanded backstory isn't always a retcon. And what you keep mentioning hasn't been changed since at least Chronicles was released which was a few months prior to Legion. Which means they didn't change the story for Shadowlands but set up the lore prior. And Blizzard has set up chronicles to be told from a biased/unreliable narrator. So things can be slightly changed with out technically being a retcon.
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Is done and ends is the same thing. The only difference is you are using quotes and I am not but both convey the same meaning.