im no expert but would think about a few subtle washes with acrylic paint rather than a straight repaint
a black wash to start with to darken the base color and bring out the texture and then dry brush some lighter shade of maybe gunmetal grey to give it some highlights ,
the batsuit was quite textured and multi tonal in the movie and the hot toys suit reflects that even having some almost bronze highlights in places ,
but feel free to disregard these suggestions if that not where your going with your figure