I note an auction in London tomorrow 17th July has a 'signed Hikashiro Sadamune' wakizashi. You can find it on google if you do a search
Now my understanding is that there is only one signed Sadamune in existence - a tanto. So this would suggest this is a great unaccounted for signed Sadamune or a gimei. The image of the nakago is very unclear as it is very badly pitted and the inmages of the blade are not sufficient to make any judgement on quality.

Interested in the process of auction houses selling Japanese blades and their descriptions, when there is obviously no paperwork.

Andy