How do I get past King Arthur?

Hint 1 of 4:

Have you read the runes on his sword?

Hint 2 of 4:

They've been changed by Vettenmyer to spell out a message for you.

Hint 3 of 4:

Vettenmyer has left other messages for you along the way.

Hint 4 of 4:

And the timeplaces where the messages are have no other purpose.