What, you don't think visitors from other worlds buy souvenirs?
All kidding aside, someone asked about the "Earth" marking on the Mili a few months back in this thread over on the BF Spyderco forum.
http://www.bladeforums.com/forums/showt ... +AND+earth
Sal's answer was "It seemed like a good idea at the time."
For what it's worth, the Golden produced C41 FRN Natives also carry the Earth designation.