The stats you have suggested seem a bit too weak, if anything. As written there's no reason to take it over a Greatsword! I think there are a couple of ways to go about this unusual piece of equipment.
1. Use stats for an existing weapon.
The simple thing to do would be to just use it as a 'Heavy Flail' by another name.
This would make it a two-handed Martial weapon with 1d10 damage, 19-20x2 critical and Bludgeoning damage. It would also give bonuses to Disarm rolls and allow the user to make Trip attacks. This last point seems a common property among flails in D&D 3.5
2. Design a new profile
If you go down this route then it would certainly count as an Exotic weapon and is very likely to be wielded two-handed. It should also be a straight upgrade over the Heavy Flail to justify needing a feat to wield it.
Here you could just increase the damage by one step up to a D12 and call it a day. If you really wanted to push the boat out, then upping the damage further still to 2D6 would effectively make it a Greatsword with some fancy properties - which seems reasonable for an Exotic weapon.
If going down this route, don't forget to keep the Disarm/Trip traits which seem inherent to all flail weapons.