The phrase "powerful tool" refers to something that has a lot of capability and can be very effective in achieving a desired outcome or purpose. Full definition
The youth you hope to help as a social entrepreneur or nonprofit leader may be your most powerful tool for helping them. (yourmarkontheworld.com)
I strongly believe that relationships, empathy, and humor are three of the most powerful tools in helping clients experience lasting change. (psychologytoday.com)
And the most powerful tool for creating this balanced state was my regular meditation practice. (mindbodygreen.com)