It sounds like you bought the game on Steam and added it to your Steam game library.
Then you bought the Loyalist Edition on the Grim Dawn web site and tried to add this Steam key to your library, but you already have the game.
If so, then what Nine was saying is that the Steam key you just got (from the Loyalist edition) can be given away to someone else because you already own Grim Dawn in Steam.
Further, the virtual rewards will be given as a separate Steam key when they are ready to be released. Currently, those virtual items have not been released. See Backer Rewards and DRM-Free Copy for info on the current state of the Virtual rewards.
Does that make things clearer?