OOC:
Actualy, Gaz, that Attack did 9 Damage. Basically, if you succeed your Damage is whatever you rolled. Then your opponent makes a Defense roll. If they succeed, they subtract the result from the damage you did. If they fail their Defense roll, they take the full amount you rolled on your Attack roll to their Hit Points.
In this case you succeeded your attack by rolling a 9 when your Target number was 14 or less. So that’s 9 Damage. The rat had to roll a 5 or less to defend against any of that damage, but they failed, so they didn’t get to subtract the result of their roll from the 9 Hit Points you scored. If they rat had rolled a "4", they would have succeeded their Defense roll and could subtract their roll of 4 from the Damage you rolled.
So the idea on combat tests, regardless of whether you are attacking or defending, is to roll as close to your Target Number as possible without going over, because the result of your roll is the Hot Point damage to you cause or defend against respectively. The only thing better than Rolling equal to your Target Number henbwould Be Rolling a "1", which is a coup. Rolling a Coup means you rolled successfully, do as much damage as your Target Number, and get to roll again to hopefully succeed again and add that to your first roll’s result.