"You look Time Lord."

Actually I think the cutlass scene works- the siren will come for you if you get the slightest cut. So all you have to do is wave a cutlass in a menacing manner at them and they'll back off. The risk of getting even a a paper cut is too great. Even a black eye would probably call her.

Although it would be nice if there was a "where did you learn to do that?" joke, which would have explained things.