Notes:

Artist's notes:

Context: the sisters of silence are something known as blanks. This means they have no souls which also means that psykers can't affect them.

Now what we see of the Emperor is a psychic projection, different people see him differently even at the same time. But a sister of silence described that she just sees him pretty much as a normal dude. There's some theories that they take their vows of silence so they can't tell anyone how he actually looks.