Nepleslian power armors are generally the toughest power armors in the setting by precedent. They're currently the 10-to-15 SP suits, that I recall. Under the umbrella of this system, that makes them Class 6. The Shield category recommends a standard of 2 endurance (I think I like "2 charges" that Eistheid mentioned better, though. Seems to carry the meaning across somewhat better), and it recommends that you assume that the Shield's class is the same as the Armor's class. It's a baseline (one which is, to be honest, inspired half from Mass Effect, half from Wes' plots). If a Game Master wants the armors in his plot to have 3 charges instead, more power to him. His arbitration, his rolls to fudge, or whichever. None of my business. I just recommend a baseline I believe is a good middleground.
It's not frequent that power armors are going to ideally have the best weapon possible for the job. One potent mainstay for the Star Army of Yamatai is their plasma rifle. Let's say it's Class 5. Say my Daisy power armor fire it at a Nepleslian Hostile. Bam, hit on shield; Shields down to 75%. It's not just two hits - I'm using a weapon from a lower class and so the shielding will be able to soak in more punishment.
Keeping on that same line of thought, let's say my plasma rifle manages to hit enough times to deplete that Hostile's shield. The Hostile has no nearby cover, and decides to make a run for it. It runs past my Daisy and I make the most out of my advantage, striking it to the left of its chestplate first, then its left shoulder, and then right in its back. My weapon is a class under, so rather than possibly destroy it, it does half its usually expected damage. Narratively, I made a smelted mess of the areas I struck, but the Hostile is still functioning, the armor - though more vulnerable in places - still protects its user, and now that the Hostile reached cover, given enough time, it can recuperate its shielding to then go back into the fray with a bit more margin for error.
In the same scenario, if my Daisy had been equipped with a Class 6 Aether Saber-rifle, I'd have reduced the Hostile's shielding with my beams twice as fast, and then when I struck it chest, shoulder and back, I'd have caused much more severe damage. If I'm a nice GM, consider the unit is in movement and all, I could rule that I smelted through the chestplate, roasted at the inner workings underneath and gave the wearer bad burns in that location. Maybe I oblierated most of the shoulder armor and burned the wearer's shoulder, or maybe I severed it off. In the back, I know there are more inner workings there, so while it might not have harmed the user, it might have savaged the thrusters, or the main power supply, or something.
Point is, though, that even in the second case, the Hostile survives more damage than its shield took on a weapon rated as capable of getting a one-hit kill on it - though I was merciful, but I'd be surprised to not have GMs fudge things a bit in the favor of PCs even if a weapon potentially can one-hit kill them. The key word here is, of course, potentially.
To me, the wonders of Nepleslian engineering is represented by them making the unit well rugged and plated enough to be class 6, which gives them in turn much more endurance than other suits in the setting have (more obvious competitors being the Mindy and the Daisy). I believe this is adequate representation for a unit like the Hostile, and it clearly can last under fire far longer than a Daisy can. That's an all around win for its portrayal.
The material of the armor can also count for something. Yamadura isn't weak. Yamadura gives you a bit more weight (more resistance to recoil/knockback can be implied in there) and regenerative properties. Say I bring my Daisy in combat against infantry. It gets fired on by assault rifles and by the end of the fight, it's crattered, pockmarked and gouged at. Had the fight been longer, there could have been breaches, and if something else happens then and there, the Daisy is badly ablated and vulnerable. But give it a few minutes, and all those blemishes are going to mostly fill themselves back in and make it look nearly pristine if not for the very abused paintjob. It's an amazing material to use for units you assume will operate without support for a long time, and it's a big boon logistically too.
This makes Yamadura a pretty good material for the Daisy, which has a good balance of mobility and defense to boot. Provided it fights targets weaker than itself, it might be able to last for prolonged stays in a combat zone, contrary to how the Mindy 2A was with its durandium armor. However, the Mindy II had advantage in using durandium - it made for a lighter base weight, which made it more compatible with the teleportation module. Also, by virtue of the teleportation module, the Mindy II would typically be used more for single skirmishes before being able to return to base to recuperate - Yamadura's regenerative properties would've gone mostly to waste.
