After a good night's sleep and reading your posts (read as: realizing how silly it is to propose a combat action almost exactly like Move and Attack), I think the "Defend~" Action is unnecessary.
See, this is why I post with you guys!
@Shaking Stuns: I hadn't quite figured it out when I posted, but here is what I propose. When a character receives a stun, he immediately makes a Stamina-RR, exactly as explained in the core rulebook.
With a high target, as explained by Nicholas in the aforementioned TGP article, it'll be often that the character will fail the roll to resist being stunned.
Then, if the character does indeed fail his Resistance Roll, he may continue to make a Stamina-RR against 150 during each of the rounds he would be stunned (this one is flat, not modified by any stuns over 1, this is to save paperwork mostly). However, if the character is no longer engaged in melee (if one of his companions jumps in and grabs the attention of the attacker), his RR target will be 100. If he succeeds, he may perform an action that round.
In theory, this could allow a "second chance" for the character to get rid of stuns but at an easier target. However, I believe that it will be hard for a companion to jump in and protect him within that first round (I would rule that the companion would even need to make a Combat Awareness maneuver for the initial stunning.), so the "second chance" will still be at 150 (which most likely would be easier, if he had obtained multiple rounds of stun, yet it's still not an easy number).
Alternatively, we could say that the roll for Resisting being stunned also counts as the roll for shaking stuns in the first round.