How is Dark Messiah connected to Heroes of Might and Magic?

I disagree... Arantir made a mistake. He wasn't entirely sane. I remember that at the end of the game, I was disappointed with the battle against him because he mostly just stood there, as if surrendering to Sareth.
And Agrael, in the "Lord" video, was recognized only after Railag told him, and before that, Kha-Belekh addressed him as a stranger.