This is such a scarce item that I didn't really recognise its significance until I started to research it in depth. (I have provided a series of web links below to save prospective buyers the same hassle !!)

It came to me months ago as part of a mixed auction lot of mostly WW1 items, and at first glance seemed like a fairly ordinary chisel. There is an English tool maker's mark on the blade (C.Hill, Sheffield and a cannon logo), but on the rear there is a German tool merchant / distributor's stamp Riebe Sohne, Magdeburg, and a metric size of 16mm (in keeping with the system adopted by the German Empire in 1872.)

It seems that Charles Hill of Sheffield operated during the latter half of the 19thC and was still in operation until at least 1911 (possibly 1917), and that Wilhelm Riebe & Son were certainly importing Hill's tools around the turn of the 20th century before eventually going bankrupt in 1933. Here'a few sample links to show dates & connections etc.

http://www.woodworkingtalk.com/f11/c-hill-chisels-history-4671/

http://www.holzwerken.de/museum/hersteller/sonstige.phtml

(Scroll quite far down on the second link to see Riebe Sohne logo and mention of C.Hill)

However, it is the handle which has thrown up the most interesting aspect. It contains two 'name' stamps - C.V.RIX and IDFLIEG. Apparently, IDFLIEG was actually used as an abbreviation for "Inspektion der Fliegertruppen" - Fliegertruppe meaning "Flying Corps" - see p.59 of this link...

https://books.google.co.uk/books?id=GxIUCQ6Yai8C&pg=PA59&lpg=PA59&dq=pr%C3%BCfanstalt+und+werft+der+fliegertruppe&source=bl&ots=0X8g4LQ__J&sig=ehD2f8aZkbvbtDnRsbfnlLUYsbQ&hl=en&sa=X&ved=0ahUKEwjfrbGv6-_QAhVILsAKHZjMA5QQ6AEIODAE#v=onepage&q=pr%C3%BCfanstalt%20und%20werft%20der%20fliegertruppe&f=false

They had a wide remit including pilot training, aircraft research design and testing etc. - see p.280 of this link...

https://books.google.co.uk/books?id=RA8ZtLhzGisC&pg=PA280&lpg=PA280&dq=idflieg&source=bl&ots=2yOdkHWfJW&sig=W6KAAWiN_oTqGbOiBVEUrkIN9dI&hl=en&sa=X&ved=0ahUKEwi-7ZOR8O_QAhWBI8AKHS41DYgQ6AEITzAL#v=onepage&q=idflieg&f=false

As for C.V.RIX, this appears to be stamped in a later and simpler 'font style' and could be an owner's name once it had been removed from military use, or it could possible be a technician's name, perhaps. I 'Googled' the surname and discovered that it is of 'Germanic and Anglo-Saxon' origin, so it could relate to an owner either in Germany or the UK. It is worth noting that the handle would appear to be an early replacement (again common practise) but it is slightly too small where the blade's shoulder meets the brass ferrule. However, I did notice that the lightly grooved grip was identical to another C.Hill chisel I found on the web, so it could be a replacement from a smaller example.

The brass ferrule has achieved a rich patina over the years, as has the rest of the handle which has a dozen or so curious diagonal impact or burn marks. One of these marks has some old paint lodged in it, but I have not attempted to clean it other than giving it a very light polish for the photos.

There is also a lone 'V' lightly stamped near the ferrule.

Incidentally, the type of chisel is quite unusual in its own right. It is a very flat-looking gouge with the shallowest curve I've seen. I have wondered if there may be a connection with the manufacture or testing of wooden propellers which were hand built at the time.

Please see my other WW1 and WW2 items, including a number of military tools.