Impotent is an interesting word to use. It has several meanings (according to Websters dictionary)
1a lacking power or strength
1b erectile disfunction or ED
2 no self control
I am curious, which of these were you mainly referring to when you posted your question?
I don’t think it would make you weak…
It might cause ED. This problem is more common as a result of pornography.
If it becomes an addiction, you definitely have lost a serious amount of self control.