1) Cogency 2) Convincingness 1) Fluency 2) Power 3) Powerfulness 4) Slickness 5) Smoothness 6) Strength 
[n] - the power to induce the taking of a course of action or the embracing of a point of view by means of argument or entreaty
noun the power to induce the taking of a course of action or the embracing of a point of view by means of argument or entreaty; `the strength of his argument settled the matter`