Imagine you playing a slow-paced shooty game, all your enemies wear heavy armour, you have an inventory with multiple guns in it, but instead of showing you a tooltip with weapon damage numbers - there is a small button labeled "test". If you push this button, a window appears, in which you can see a fixated weapon and a machine that slides armour plates before it, one after another. Then the gun shoots the plates and you can observe what a particular gun will do to an armoured foe, and a magnitude of its effect. For instance a particular weapon might pierce the armour easily or dent it, crack and shatter it or bounce, melt it or reflect.
Obviously after some time in the game, you, the player, will be able to generally predict what a particular weapon would do, but would it remain too much of "style over substance" ? A neat visual idea, but a bad design and interface choice ?