Sharpen wouldn't affect your grasses, so if you are saying the grasses died slow or poorly, it would not help to have Sharpen in the mix.
In very dry, slow growing conditions it is very common for glyphosate (Roundup) to not really affect the well-rooted grasses much. I sprayed a patch 5 years ago, to put corn in, the grass came back. It was very dry, and hot, the cool-season grass was basically dormant and the glyphosate only killed 30-50% of it. It was a wet part of the farm, I still make hay off it, can't tell I ever sprayed it by the next year already, grass filled right back in. Typically glyphosate is an excellent grass killer, but a good sod type grass you can run into situations it won't take it out.
I don't know what crop you were planting or when you sprayed. You can send in samples of your weeds to a testing lab, probably your soils testing lab would handle this. If this happened in spring and you are looking into it now, then it might be kinda tough.