take it into photoshop, .., bt coincidence im trying to get better highlights on my 3D dart.., i just did this
image.adjustment/desaturate
image/adjustment/shadows and light
image/adjustment/levels
dont know if thats how the pros do it but play with these settings
i hope this is what you mean, you ae trying to get highlights or specular?? .., maybe a little blur .., and comp them together
you can see the changes as i went through the adjustments
you could use the settings in maya too, plenty here can supply that too
im trying to get spec on the wire
take it easy and life will be easy