Hard to tell. Harald could only be hurt by descendants of that dumb mage that cursed him.
If we give Sentry his highest showing he could simply erase the rapist from existence, but barring that I do not see Sentry actually harming him physically. Of course it goes the other way too, as he can't really put down Sentry on his own.
Also Harald can't even fly lol. Sentry bfrs ftw.