What's weaker? Expressing your emotion through tears? Or... being afraid to express your emotions, therefore hiding them so other people don't know what you're feeling?

Crying is only a sign of weakness in people who think it is, not because of the crying, but because of what they're afraid it will reveal to others.

Mind you, having mastery over your emotions isn't a bad thing either. If you choose not to cry because you don't feel it's appropriate or the right time, it's different from not crying because you're scared to cry.

In other words, crying or not crying is neither inherently weak or strong. The reasons for doing so or not doing so make all the difference.