Perhaps giving higher tier items some kind of special that is only usable once identified would work? For example, a Legendary Dagger that has a 10% chance of instantly killing the victim, or an Epic Longsword that has a 10% chance of a critical hit, or Armor that when your opponent hits you has a 10% chance of knocking the enemy back, etc. Another option is simply not showing the tier tag at all until it is identified. Or even do both!