I searched about this question on the forum and could not find the answer.
The RMC state that stun effect is applied immediately unless the PC has used more than 50% of his activity for the round. In the other case, the PC is at -25 for the remainder of the round and the stun will take effect on the following round.
So here is the scenario:
P1 and P2 are in melee combat
Initiative: P1 attacks P2 first
P1 declares weapon OB:100% / DB:0%
P2 declares weapon OB:55% / DB:45%.
P1 attack results in P2 being stunned and unable to parry.
Now the question:
Is P2 stunned and unable to parry immediately, so he cannot attack in this round?
The argument for this option is that P2 used only 45% of activity for defense, so it is below the 50% threshold of the stun effect time rule. In this case, the "unable to parry" part is lost, because P2 actually parried with part of his OB. However, in his turn, P2 cannot attack and is at -75 for maneuvers.
The other option could be: because P2 has already parried with some part of his OB, he is at -25 for the remainder of the round and stunned and unable to parry on the following round. The problem with this approach is that P2 could kill/stun P1 attacking at -25, so P1 would not benefit from the stun he inflicted.
What do you think is the best option?