Since the question is only about how the Player1 kills player2 message:
First, each hero is saved in an array using the player number then just make a trigger that handles Unit Dies event, condition would be dying unit is a hero
then on the actions just do
tmpP1 = Player number of triggering player
tmpP2 = Player number of owner of killing unit
Show text - Player Name of tmpP2 + ( + Name of hero (get from array) + ) + pawns + Player Name of tmpP1 + ( + Name of hero (get from array) + )