Just so that people don't misunderstand the question the 9" titanium armwand became standard from the mkII onwards (although some of the early ones may have escaped and were still ceramic).
Some felt the ceramic ones sounded better than titanium versions but I'm told the reason Bob switched to titanium was that folk kept accidentally dropping and shattering them on solid floors and surfaces. :O
So what you must be referring to on the 9" wand is improved wiring and, possibly, connector quality?