Ampere

I'm confused about why the Sand Lord wanted the sand masters gone? I mean how much do they really effect him.

After reading all the books about how the shards get their specific investiture. I don't see how lashing is of honor or how steelpushing is of preservation. Do all the shards have the same powers and they just choose the investiture or it somehow looked them personally? Was Ati like I thing metals dope so I'm gonna have people swallow it if they want to use investiture?