Iago, could you maybe give an example of the updated Riposte in action?
I have the stunt. It's my turn in the exchange. I choose to go full defensive, because I have feeling I'm outclassed, and this dude really has it in for me. +2 to my defenses until my next turn.
Dude attacks me with a sword (I've got one too); he rolls a Great (+4) attack (as I feared). I've got I'm only at Fair (+2) Weapons, let's say, and I'm using it as my defensive option. If I roll +0 or worse, my defense is 2 (skill) + 2 (full defense) = 4, not bigger than his attack, so he's gonna hit me square up and I'll take the margin plus his Weapon:2 rating in stress.
If I roll +1 or better, I defend (because my base is 4, as calculated above) just fine. If I want to activate my stunt to turn my defense roll into an immediate attack, though, I'm going to lose the +2 bonus from the full defense *on the attack*. Let's run that scenario first:
I roll a +1, added to my base of 4, so my defense is Superb (+5). Against his Great (+4) attack, it's a successful defense. I activate the riposte, so that defense roll now becomes my attack roll and vice-versa: Superb (+5) attack vs. Great (+4) defense. BUT, I lose the +2 full defense bonus in this conversion so it actually comes out as a Good (+3) attack vs. a Great (+4) defense. That's a miss.
But if I roll better than +1, then I'm still gonna get a Great result on my riposte attack even without that +2 full defense bonus. The riposte attack will connect with his Great defense (his attack roll that I've turned on itself), and I'll get to add my own Weapon:2 to the margin of success.
In order to do that riposte, though, I've had to sacrifice the next exchange's action (essentially I used it in advance for the riposte).
So, next exchange, it comes my turn, but I don't get to do anything. I've already done it. If the guy comes at me again, I won't be operating with a full defense bonus because I wasn't able to re-declare a full defense as my second exchange's action.