Here is a model of a brass knucles declined in 3 versions:low poly, mid and high poly.

There are models in quads version that can be subdivided and a triangulated version for each poly count.You can use this object for games or rendering. Model is manifold and .blend is ready for UV unwrapping(conviniently placed seams for non over lapping UV unwrapping)

You can contact me if you need a format that is not included