This is by far the worst "They have it in Game X so it should be in Skyrim" example ever. Warcraft 3 is an RTS for Chris's sake. It doesn't have to have a good animation, all the attack's are based on dice rolls. Half the time most attacks don't look like they connect when they do. This is about collision detection, something that Warcraft only used to keep you from building in certain spots or walking through buildings and other stuff. Just wow...
I would love for flails to be in Skyrim. They would either have to have their own attack animations for the ball to keep it from hitting the wielder or just make it so it can't hurt the wielder (which could already be a factor, we have never had a weapon that could hit the person using it in one of the newer games. The only problem is with an animation it looks silly most of the time and if you make so it can't hurt the person using it it could still get wrapped around other things pretty easily and get stuck. Some things on chains glitched rather easily in Oblivion like some guard tower torches and stuff like that.
The animations looked fine, though. All that needs to be reworked is implementation of real hitboxes accompanying the animation.
And for your second paragraph... be careful where you swing it. I think the trajectory of the ball should be physics-based. Anything in its path gets hit (Hitboxes have been around forever). I don't think it would be too hard (relatively speaking) to ensure the chain doesn't get stuck on thing.
What's with the obsession over spears? They've only ever been in
two of
six Elder Scrolls games (Battlespire had the Spear of Bitter Mercy for its "Wild Hunt" segement, and Morrowind had spears.
ARENA,
Daggerfall,
Redguard!, and
Oblivion all lacked spears). They aren't a "Staple of the Series that have been removed to dumb the games down.