From what I understand of the history of a sgian dubh is that it was used for hunting much the same way the scandies in Scandinavia. I would not see any practical purposes for a double edge knife for field use.

When using a knife for skinning and capping a small, easily maneuvered knife is normally what is preferred. I am not sure but the notches I would guess they are decorative as they would be a pain to clean out after processing an animal. They fall into what custom makers call file work -



Here is an interesting page from a collection of one of our knife maker's forum's local historian.



Jim