Tooth and Claw (2006) (2006)

Sir Robert: Nevertheless, that creature won't give up, Doctor, and we still don't possess an actual weapon!
The Doctor: Oh, your dad got all the brains, didn't he?
Rose Tyler: Being rude again!
The Doctor: Good, I meant that one. You want weapons? We're in a library! Books! The best weapons in the world! This room's the greatest arsenal we could have - arm yourselves!