Since my name was mentioned, I'll weigh in - I can see some darker patina at the top and lightening up as the eye goes down. I am in agreement that in this case there may have been something there with the reminents of pitch present. My thoughts are of something that can easily be taken off and sold, like repoussed/chased silver or even a little gold. Intriguing puppy (woof !

).
I've also noticed that the hilt has been re-wrapped. May have been silver bands on it originally?