One thing that keeps a mod from being "heavy handed" is one I have employed against myself on forums that I have moderated in the past:
I would never attempt to moderate a thread in which I was a participant. I find that it is much more difficult to be objective when you are immersed in the discussion at hand.
Of course, I was the lone objectivist on a Liberal-leaning board that dealt with credit issues and financial advice. The policy there was "no political threads." I noticed that threads frequently were political, and that other mods and administrators were participating. The other mods would only close threads or delete posts that were not in keeping with the liberal viewpoint they all shared. In trying to keep dissension amongst moderators private, I pointed that out in the mod-only forum. I was removed as a mod and banned from the site.