Settra is unironically the epitome of the ideological esthetic that WH comes from. He is a man with so strong a WILL that he will not die and leads his empire from beyond the grave. It's a very positivist, man over everything, shtick. And WH is, at its core, all about that shit. It's a positivist world wherein man's will and ingenuity are faced with the superstitions of old. The twist is that they cannot triumph... Settra is ironically kind of a hope that they actually CAN. He represents supremacy of will, kinda Hitlerian in a way, but well, das what that philosophical tradition lead to, so it only makes sense.
