That was my initial reaction too. Like holy ****, they really did it. But in retrospect, I'm more excited for what the future holds now since we'll get to see the original team come back together for presumably one last time.
But yea, when Strange bargained for Tony's life I was sitting there thinking that Thanos would HAVE to use the time stone to undo the stabbing cuz you're right, that blade was big as hell. Went through some major organs and arteries for sure. So when he sprayed himself with some nano-particles to patch himself up I was like "errrright.... I guess they can heal major trauma, no big deal"