Here is a site for a similar sword with a German blade from Rubylane dealer and an ID of the "G.G" mark. "GESETZLICH GESCHUETZT stamp. This means "protected by law" and is a trademark stamp." Apparently, many blade makers used the mark.
https://www.rubylane.com/item/61838-...ik-II-Imperial
Here is a discussion from another forum.
http://www.swordforum.com/forums/sho...fy-my-swords-1
Hope this helps.