After re-reading Nick's post, #66 on this thread: http://www.warrelics...gunto-676112-7/
it sounds to me like this could have been carried by an NCO. The order allowing NCO's to carry family swords states the rig must "be suitably converted to resemble regulation specs." We have all seen numberous variations on the tsukas of converted blades, but having an aluminum handle doesn't appear to be one of them, so I assume conversion kits only used officer-stlyed tsuka. Of course many of them used the original tsuka and simply replaced things like menugi, tsuba, seppe, etc; but some of them have full IJA tsuka.
I would say this one falls into the "it could be any option of many" on how the NCO tassel got there.