We're back from Pennsic, which means More Swordnerdery! Yay!
Before I start to kick around thoughts like "how accurate are the plates in Fabris, anyway" I'm just going to plow ahead with his guards in Second because I want to keep making forward progress here.
As a reminder, we can see his four guards in Second here and here, and his descriptions of lunging and passing in Second here. The first two guards in Second are pretty straightforward, while the second two are a good deal stranger upon first glance - so we'll dive through them in order.
The first guard in Second is what you end up with when you take the first guard in First (the imperfect one on the left), rotate your hand, and lower your arm. Fabris points out that it's easier to maintain that guard, and that the weak side is now the outside rather than on top. This is another highlight of the concept of the sword being stronger in the direction towards which it points - while we end up in Second while opposing towards the outside, this guard is initially stronger towards the inside. That said, you can parry toward the outside with the forte as it's still far enough forward even with the relatively wide position of the arm, and if you move into Fourth you can parry to the inside. Fabris does say that even though there are some good ideas with this guard, the wider step leaves your right knee somewhat exposed, and the next guard in Second "is much better than this one."
Looking at the plate of the second guard, we can note some changes immediately. The stance is narrower, and the arm is much straighter than the previous guard. Fabris notes that the arm change is important, because since a Second is weaker on the outside, you don't want your opponent attacking that line - even if, as he notes, it is the most covered.
Fabris feels that due to the sword placement and body posture in this guard, the only clear opening should be your head over your sword. Your lower body is safe due to your posture. Fabris does note that your opponent could feint toward your head and redirect to a line below your sword, which is always a thing to beware of if you've really only got a couple clear openings. If we ignore cuts for the moment, you can parry most attacks in Second. Inside thrusts should be parried in Fourth. Fabris notes that these defenses are easy due to the straight direction of the sword - something which also allows you to make very tiny cavazione and counter people trying to find your sword. Similar to guards in First, Fabris closes by noting that keeping your arm in this posture is tiring over time.
The third guard in Second is really one of the first guards in this manual that will make people blink a lot and wonder what the hell Fabris is thinking here. The big thing to note is that moreso than any other guard we've seen yet, this isn't something that you settle into without context. Fabris wants you to settle downwards into this guard as your opponent gets closer. When your opponent is within measure, your body should be as low as you can get it and your sword as far back as possible while still keeping it on line with your opponent. Fabris points out that you need to keep it straight so your opponent stays on the inside. Also, keep your left hand way back to help keep your lucky face safe.
The very moment that your opponent's sword penetrates yours, you should strike towards the inside in Fourth. (Fabris notes that "your right foot forms a transverse step" so that "at the moment of your attack, your body will be out of presence before you even move your feet." I admit, I'm still working on exactly how that sorts itself out.) If your opponent's sword is directed towards yours, your body should go underneath, and you should push in Second against their debole.
The last guard in Second is also one of those guards that makes people wonder what's up, but generally not nearly so much as the previous. Similar to the previous, this is also a transitional posture - Fabris states that you should really move from a Third into this guard to invite an attack by your opponent. If they attack you while you are transitioning into this guard, cover with your left hand and straighten your sword into them. If they wait until you have formed this posture, you can use a girata and strike in Fourth or parry and respond in Second.
Fabris does make it very clear that this is not a posture to hang out in; form a new guard without stepping (so that you can move backward or forward to parry or counter as you need).
That's it! The next entry will either be going through the guards in Third, or maybe going over the lunges and passes from First and Second. Probably the latter, just for a bit of a break before More Guards.