I received the 500/500 hammer blows achievment during reaper death shroud, and then realized every kill in shroud was indeed increasing my hammer kills. Not sure if a bug or not but bringing it up just incase…
Hammer achiev while in Reaper Shroud
Not a bug. Reaper Scythe is (mechanically) a Hammer skin. You can see for yourself:
[&C7kXAAA=]