That´s a great Idea from EIT_Turtle
They need to reward a player weekly/monthly/annually for staying in the same world. Maybe not an item, but maybe some type of account based title chain that resets whenever you change worlds.
If they can’t think of a name, then maybe use the GW1 title rank system.
New Transfer = Squire of “Server Name”
1 week = “Server Name” Supporter
2 weeks = Friend of the “Server Name”
1 Month = Companion of the “Server Name”
1 Year / 2 Years = Savior of the “Server Name”
I think this way you can see which player can be a potential spy.