Hello Apolaki, This is a very interesting piece that you have acquired. The ingenious use of an old hose fitting as a ferrule is most inventive and a great example of the old saying "Waste not want not" being put to practice. As for age I would place this piece as being made sometime in the second quarter (1925/1950) and possibly even the early part of the third quarter (1950/1960's) of the 20th century. This is just my general opinion on this and I am sure that others will be able to narrow down the timeline a bit better for you as to when it was actually made. As for your last question, I am not sure what black marks you are referring to?
Best,
Robert