I don't see how it can kill you when it's no longer part of you. It's gone, that's why you cut off half of your arm. As far as this DLC goes, it was excellent overall. I hope Bioware does Epilogue DLCs for all their games in the future, personally. This ending gave me such mixed feelings. I totally wanted another game as the Inquisitor after this, Solas just made this personal god dammit! On the other hand...pun intended...It felt like a MUCH better ending, and thus lead in, to DA4: Fun Times in Tevinter. I really hope the Inquisitor takes an active Chess Master role in the game. They command the fight from afar, the new PC makes it happen, since Quizzy can't anymore.
Because, if you actually paid any attention to the story at all, the Mark isn't actually in your hand. It's a part of you in a metaphysical sense. It's tied to your life from the Summit on, and without it, you'd die. If it were as easy as chopping off your hand, Corypheus would have done it. Solas didn't take the Mark away, because if he could have done that, there would be no point in removing your arm. He just stopped it from spreading. The Inquisitor is still going to die from it, and nothing was accomplished at all. This has nothing to do with wanting to play the Inquisitor again, although this was clearly done so you couldn't, and a lot more to do with the fact that one day, the Anchor will kill you.