I wouldn't say that Hillary was "powerless", because she DID have positions in the government that were able to wield influence, but, she didn't have absolute power (as Trump would like you to believe).
As First Lady, yeah, she did have influence on certain matters, as well as may have had a talk or two with her husband about some policies, but she's not the one that signed them into law. But, speaking of wives who have had a significant influence on their husband's presidencies, wanna talk about Nancy Reagan? How about all the ladies in this link?
Top 10 Most Influential First Ladies of the United States
As a Senator, yeah, she did have the ability to bring up legislation, as well as try to influence others to get legislation passed. However, she was just 1 vote out of 100, and anything that the Senate passes, also has to be passed by the House, and then it has to be signed by the President. So, yeah, maybe a LITTLE influence, but not enough to enact legislation into law by herself.
As Secretary of State, yeah, she was a direct representative of the United States and the president to foreign nations, and yeah, she did negotiate with those countries over certain things, but they were only things that the president told her to negotiate, and she didn't have the final say in whether or not a treaty was struck. That responsibility lies with the president and Congress. SOS has no say as to whether or not a treaty is approved, they just negotiate it.