There are only certain lua triggers and I don't believe that the game triggers a lua based on a PVP kill. Perhaps in arena, but not in the open world. Next time use help thread bruh.
but you must make specific related value for the dead player like if he has item in his bag or have buff or his name has value in global variable or the dead player is in specific area according to x , y.... but the script will applied on the dead player not the killer so you can make a drop_item() script