Huntsman and Fail-A-Nature both annoy me. I don't think they're overpowered, they just bug the hell out of me. Before I start, I'll just explain that I main Spy, so weapons that are designed to be effective at close range are bound to grind.
Frst off, the Huntsman, as has been said above, doesn't quite work as a weapon that gives headshots, and I'll often think I've dodged an arrow and see it whoosh past my head, only to suddenly have it disappear as I watch it and give a headshot against me. Very annoying. Also, it'll almost always headshot if fired point-blank, regardless of where I am in relation to the Sniper or where they are facing. I've been headshotted several times when I was stood behind the Sniper (I also get that with melee weapons, the Ubersaw in particular).
As for the Fail-A-Nature, it has got to be THE most annoying weapon in the history of the universe. This gun has been responsible for some of the worst fails I?ve had while spying, and the worst part is that I couldn?t do anything about it. I don?t mind so much when I get flamed by a Pyro, because I can and do blame it on them being paranoid and/or spammy. When I bump into people, it?s simply a matter of bad luck, or that it was a stupid place to be in the first place. However, the Fail-A-Nature immediately turns any spy-check into instant death. One hit from it and not only are you hurt and your presence revealed, but you also fly back a good two or three feet and well away from anyone who you could have backstabbed, while being instantly paralysed while in the air and losing all momentum, making it nigh on impossible to run away once you land. Also, it has ruined a good many stairstabs when I have jumped, only to find myself blasted into the air as if by a rocket-jump. The huge spread of the FaN also means that it is almost impossible to avoid. If a Scout shoots somewhere within the same map as you, chances are they?ll hit you, and this does not a fun game make.