IIRC two different shops built Nemesis phasers, and it appears there are two "correct" colors...
Here are some photos of screen used phasers... in comparing the stunt color to the hero, it looks like the hero is a lighter shade, more like regular 7173 (or the Endgame color). I don't know if that's because the photo lighting is different or more likely ISS used a different color when they built the hero.
Nemesis stunts (I think made by HMS since there's no cowl seam line?)
The color of the stunt phasers is slightly darker and more blue than the regular 7173 and resembles the old Plasti-kote 1004.
For a modern equivalent I used Duplicolor BFM0225 Medium Charcoal Met on a recent build as it looks close to that old Plasti-kote 1004.
Here are some photos I took comparing the old and new paints -- the static one is an old build using the PK 1004, and the hero is the newer Dupli-color. Not exact, but close enough for me. Color changes a lot with lighting.