There is an increasing need for ultra-precision in machining various materials employing modern methods in today’s competitive industrial environment. Electric discharge machining is a popular and efficient advanced machining procedure for super-alloys, composites, and resistant to heat steels. In the present investigation authors have investigated interrelation of electric discharge machining’s input and output parameters. To figure out the surface quality, electrode wear rate (EWR), and cutting efficiency of AISI420 stainless steel. Gap voltage, duty cycle along with current and pulse on time are considered as machining variables. We used Taguchi’s orthogonal array (L16) technique for experiment design and response surface methodology for parameter optimization that minimize surface roughness and electrode wear rate while maximizing material removal rate. The currently used models of mathematics have been tested for efficacy using analysis of variance. Furthermore, the present investigation uses the weighted-Grey relational analysis (w-GRA) approach instead of the conventional grey relational analysis (GRA) methodology for achievement of optimized responses. Using the w-GRA approach improved EDM output responses, according to the trials, and the development in grey relational grade is detected at 0.2382. As an outcome, there are a number of significant applications in industry that use the proposed w-GRA approach. The experiments verify the method’s efficacy in improving machining.