He remembers this move vividly, as he does most things he'd witnessed Helen actually do in person. It means he doesn't bother to move anywhere but away from the arc of the swing he can follow, though Rex's leap and reach mean that even with Ekkehardt's speed and reflexes, he barely avoids being beheaded.

(Not that being beheaded would stop him. It hasn't before. But, if Rex's multiple dead dream versions of him are any indication, he might not remember that, or perhaps he doesn't know it.)

The blade nicks his throat in a way that would have bitten into the major artery there, if he was alive. But he's not, so it does little. He claps his hand over the disruption regardless, partially out of habit to keep up his imitation of life and partially because this is a dream, so phantom pain is a little more real.

"If fighting is how you spend all your time, it's no wonder you're so exhausted."

He'd say you can't possibly enjoy it, but he's certainly seen that Rex enjoys fighting. This is something different, deeper.