Sounds more likely that you will damage the scissors than the racquet. A good shear cutter is more appropriate for cutting out tennis string.
I am curious as to how you know that the tension is wrong. A typical tension tester measures deflection of the string face and is only intended to provide insight into a string's relaxation over a period of time. The device reflects a relative number and not pounds, that denotes tension loss. (1)
What most people don't realize is that a fresh string job will lose 8 to 15 percent of tension in the first 24 hours without even playing depending on the string, the type of machine used and even the technique used by the stringer.
For example: I take my stick to the club pro for restringing. I want my Prince TT Warrior strung with Wilson Sensation at 60 lbs. My club pro uses an electric (constant pull) machine. Two days later I pick up my racquet. Based on extensive testing by the United States Racquet Stringer's Association, the tension of my string will be about 55 lbs. If my club pro had used a spring-based machine the tension would be even lower (between 52 to 54 lbs). (2)