Then I took the weight out, put the washer and screwed the weight back. Started the engine and sure enough, buzz is gone. I'd swear the bike got at least 10 HP more! 
This makes a lot of sense, especially since I had mine off yesterday to install the Throttlemeister, so I saw exactly how the weights are attached.
On other bikes, the bar end weights are affixed into the opening with an expanding rubber fastener, such as those used in other applications. Obviously, on the C14, they are bolted directly into the end of the bar.
Essentially, the bar weights affect the frequency of the vibration. It makes complete sense that changing the way the weights are affixed, by adding or subtracting washers, will absolutely affect the frequency in which the vibrate. It has to.
By adding washer(s), the length of the bar ends is extended, changing the frequency dynamics. Also, when the bar weight body is flush against the rubber grips, it will clearly respond differently to vibration, than if held away by a narrower point.
This is akin to other bike's vibration solutions like filling the bars with a lightweight, expandable material, etc. It all changes the vibration frequency of the material.
The part I didn't think of until this excellent material was posted, is the almost infinite adjustment ability of this trick. Heck, one could go down to a vacant lot or less traveled road with a pocket full of washers or shims and Allen wrench -- and solve most vibration issues with a few experiments.
Kudos and plaudits to the author!
