Well, it has to do with the Dwemer, so me being a Dwemer fannatic it's easily a favorite.
Yes, you are remembering correctly.that would be the one where you have to bring him 10 dwemer cogs iirc
I was very disappointed by how incredibly weak Keening is. Using a weapon that will drain 10 points of health, magicka, and stamina for one time only(it's not rechargeable) does not sound like an awesome reward in my opinion.
That's the main reason I think it should have been one of the better weapons in Skyrim.I agree with you on that. But it is a major piece of history.