One time I was playing, and using the Hammer because it's my new favorite weapon, but, sometimes, when I hit other robots they wouldn't take damage at all... and sometimes only a single voxel would be removed if I hit them square on the torso, and this has led to a lot of early deaths. (I mean, my high score is fifty-something Titanium, now I barely get past Gold XD)

It may be an optics issue. Try increasing the mouse sensitivity setting and swinging wildly to get used to the damage arch. - That's how I got better with those "near hit", "barely struck" attacks, the sensitivity trick. - That may also help you visualize the hammer 2 and 3's damage arch, in so getting betting at dodging them. They also do adhere to a certain timing, which once you able to anticipate lets you take them out relatively easily with the sword. - Hope that answers your question or at least helps a little. :-)

-Cheers