With Bungie you never know if it's actually a key to a Easter egg.
The Stranger hands it to you. This could be Bungie's way of saying this is important for other things.
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Most games dont let you delete quest items, but that would make it obviously important and ruin the surprise....but also, why would a gun be the key to something? thatd be a super lame plot device in a game where weapons are completely expendable and become obsolete within hours.