It's actually called a Domination Band. The a'dam was mostly likely an attempt to imitate it and adapt it for women
That’s quite a name.
It seems implied that it was created as part of the post-Breaking attempts to find some way to control men who could channel, now that saidin was tainted, right? At which point...well, why wouldn’t something like that be created? That, and then eventually the a’dam, adapted for a different purpose, and considered impressive by at least one of the Forsaken, discovered as it was in a less ‘advanced’ Age (but one in which there was much greater need...)
Anyway, thinking about this, what I’m curious about is one of the other things one of the Forsaken has been surprised to see discovered by these ‘primitives’: the Warder bond. Was that, perhaps, part of this same research? The result of another attempt to find some way to control or limit the men now doomed to go mad, to prevent that and the inevitable damage?