Thank you everyone for such wonderful insightful responses.
Jeff, applying KISS method
(which I really like) is the best policy and in this light your observation and interpretation seems most plausable to me.
As a matter of fact it was exactly in this fashion ("a gold filled hole") that this mark was described to me by my friend who personally examined the saber.
Tom,
Not yet having the chance to examine the sword in person I cannot answer if the cross hatching on the spine is a form of decoration or a sign of mechanical abuse. The "step" (or a double step as it is repeated at the point of the blade forming a "cut out" in the middle of it) is a common feature on Polish sabers and the book by Jacek Gutkowski cited above shows a couple of examples of Tatar sabers with this feature.
As to the spine markings if we rule out tamgas then a possibility of them being an Armenian maker's marks should be examined, perhaps it represents the letter "h".