Yeah, if you want a less intense color, it may seem like a good idea to add white. But a grey can create some very nice desaturated results. As I said to BAM, I try to mix in greys that have a similar light/dark value to my color. So for the basic red, ideally a medium grey. For the red highlight, a light grey. And for the red shade, a dark grey. That way you aren't changing how light or dark the color is, just how saturated it is. Also, that way you can also more easily control the saturation for the highlights and shadows too. You can decide if you want to go 50/50 color and grey for all three or perhaps you want the color to be more saturated in the shadows (75/25 color to grey) and less saturated in the highlights (25/75 color to grey). I used a similar approach on the coat for my dwarf pirate.
By the way, when I initially suggested the color shift, I was thinking how the weathering would look over the desaturated red vs the strong red. But, seeing this stage, it also contrasts very nicely with the blood on his face. I feel like that red stands out more than before. I think the new color definitely fits the piece well. Going to be a strong entry at CB to be sure!