In WFRP 4e, the rules aren't clear if a defender who wins an opposed Melee (any) test in combat will do damage to the attacker.
A first reading of the combat rules on p. 158:
1: Roll to Hit
Melee: To attack, perform an Opposed Melee Test with your Opponent (both you and your opponent Test your Melee Skill — see page 126). Whoever scores the highest SL wins. If you win the Test, you hit your opponent and gain +1 Advantage. If you lose the Opposed Test, your opponent gains +1 Advantage and your Action is finished.
The last sentence ("If you lose...") does not include the key phrase from the previous: "you hit your opponent". This would clearly seem that the defender doesn't get to make a hit and do damage, and your attacking Action is finished.
However, when you read the Opposing a Melee Attack box on the following page (p. 159):
You can Oppose an incoming melee attack with more than just your Melee Skill. The most obvious choice is Dodge, which allows you to avoid incoming blows, but Chapter 4: Skills and Talents lists many other Skills that just might be useful in combat, including Intimidate, Charm, Leadership, and more. If your GM thinks it’s appropriate for the situation, and you’re happy missing out on the opportunity to score a Critical Hit against your opponent, then why not give it a go.
This clearly indicates that the defender in an opposed melee test in combat can score a critical hit — so the defender winning the opposed roll does make critical hits. This is further confirmed below, under Criticals and Fumbles:
Any successful Melee or Ranged Test that also rolls a double causes a Critical. This means you have dealt a significant blow, and it even happens when you are the defender in an opposed Test.
So, obviously, when the defender wins an opposed test, the attacker's Action doesn't simply end, despite the wording in the rules for making a melee attack. At the very least, critical damage is resolved first.
Does winning an Opposed Melee Test as a defender also do normal weapon damage, just as if you were the attacker, or is a critical hit the only damage the defender can do?