You've killed us both

[hollowleviathan]

I still maintain the blood sacrifice theory. The alleged disproof being that you die when you help Agrippa through the portal despite Alexander's death, but in this scenario, you did not directly cause his end like stopping his portal summoning ritual does; we don't know what Agrippa, or Weyer does in the short time he's been freed to whatever plane that is. (Nor do we know that, if you do indeed die, it's the Shadow. Agrippa could be severing you from your body to yank you into his plane.)

More simply, the intent of that ending is that you deferred your fear and your anger to the plan of a wiser being more attuned to the orb and their mythos. The Shadow is relentless and murderous. In the ending where you directly end Alexander, you embody that animus and have by thwarting him returned his orb and yours to the guardian.