When you choose a Shard Shield in the vet rewards menu, you'll get a deed in your backpack. You can use this deed to place the corresponding Shard Shield in your house:
http://i47.***********/2zfiky1.png
Doubleclicking the shield will yield a transfer token to the corresponding shard in your backpack (once a month; you can get one immediately after placing the shield):
http://i48.***********/2nvb55.png
Now, you can take the tokens to wherever you go. The transfer to the corresponding shard will start when you doubleclick the token. As claudia-fjp wrote, you got to be in a safe location for that.
Differences between Shard Shield and the fully paid tokens:
- you can use the shield token only for a travel to the shard mentioned on the token - the paid one will present you an additional menu with all shards (except SP, Mugen, TC)
- all the pets you take along must be stabled and can therefore not carry any goods for you. This limits the transferable goods to what you wear, what you got in your backpack and what is held in your bank box.