EXPCalibur Location - Dying Light Easter Egg
The EXPcalibur is a weapon that is only good for the first couple hours of the game then is replaced by most items you can buy from shops. This Easter Egg is a reference to King Arthur and the sword in the stone story. You can find this Easter Egg in the southeastern most portion of the Slums just off the coast.
Swim to the southeast and you'll find a small island that appears to be nothing but a large boulder from the direction you're looking at it. Climb ontop of it and on the otherside you'll find a corpse with the EXPcalibur sticking out of it. When you decide to pull the sword out of the stone you'll need to hold whatever button is your action button for 2 minutes. You'll see the bar slowly going up if you watch it closely. After 2 minutes Crane will pull the sword out of the stone and it will be yours.
Dying Light EXP Calibur Location (Video)