One suggestion that I read and sort of liked is that angreal and sa'angreal could not be made directly by channelers but required the use of specialized ter'angreal. Ter'angreal can create stuff, we known, such as the Warder-cloak cloth, so why not?

But, of course, we have no idea of how they were actually made. And just as well. Imagine one of the sides learning how to make angreal or sa'angreal for every one of their channelers. Too many characters have already got one of more of those already, IMHO.