I've been scouring the internet for this answer, yet no one can give a definitive answer.
what i do know is:
1: its from special orders
2: its not an E3 code
3: its not the bungie bounty emblem
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Its from a set of codes. Google free destiny codes and youll see a list of like 27 items, they have shaders emblems and grimoire cards (they were released before beta so most the grimoire youve probably unlocked already, one card was for the Gjallahorn)