Have no fear! And when you don't, it won't be a big deal to tell the guy that as a social human being you see it as your natural responsibility to make sure those around you are okay. At least, that's what came to my mind as a quick response. But I understand, all this depends on the finer details of the situation. And since you felt the need to take those knives to bed with you, I'm guessing that there were some other bad attributes of this guy and the air around him. Maybe I wouldn't have said anything at all to him, if it was me who had to share a space with him.
I think of saying many things to him but I don't speak Portuguese and that limits me as there will be so much interference and misunderstanding. For the moment I'll just sit it out and see what happens...