Hey! Sorry I'm so late getting back to this.
So yes, as Yemin said, they should be great chains. I think the one I have weighs about nine pounds. more than a greatsword and probably even larger than one. Definitely harder not to kill yourself with, I'd imagine.
But my concern was that by changing the category it falls in, wouldn't that screw those who have already purchased things like weapon focus, weapon spec, etc. in chains for use with this specific weapon? There probably aren't many, but they're definitely out there.
So that's why I thought just changing the helpfiles to read accurately might be the best option. If the above assumption is wrong, then by all means, I'd advocate making them great chains as they should be and as they were likely intended to be.
But yeah, they are pretty rare. And even rarer to actually be used. So you probably won't see many more than myself who cares about them for their own use.
<digression>
Jarngron. That last bit reminds me of a weapon my tabletop halforcish barbarian used to wield. It was a ridiculous let's-be-as-not-serious-as-possible sort of game, and everyone had the most useless magical gear ever. +3 Greatclub of cure moderate wounds. The mental image I get of ten tons of raging muscle beating the absolute crap out of his friends just to gamble on keeping them alive is still more hilarious to me than it probably should be. I'm such a sick individual.
</digression>
Nascentes morimur, finisque ab origine pendet.