Galand and Melascula came out of nowhere. I can understand Melascula because the last time we saw her she was in one of Merlin's test tubes, but I thought Galand was killed by Estarossa. I feel like Grayroad would have made more sense, but maybe Nakaba wanted to have Melascula team up with her former partner again. There could also be an in-universe reason for this since Galand did attack Camelot and he also got Merlin petrified. Perhaps the two of them wanted some payback? Either way, having two of the Ten Commandments show up here is a pretty major development. I have to wonder how they're going to be dealt with if they really are stronger than during the events of NnT? Either Lancelot really is on the level of the Sins, Gawain is going to start using Sunshine more effectively or Meliodas will have to step in. The third option seems like the most likely one to me, simply because right now the readers who started with the sequel have no idea just how absurdly powerful Meliodas actually is. Of course we could also be dealing with a fusion of multiple scenarios, like having Lancelot or the entire FKOTA get their asses kicked for a bit before Meliodas steps in to showcase how much room for growth the quartet still has.
The situation with Galand is a bit confusing to me. I always thought he died when Estarossa shattered his petrified body into pieces. That was consistent with how Estarossa foreshadowed his intention to kill the TC to steal their Commandments and with how Galand stopped telepathically talking to Estarossa as soon as his body crumbled away. Is the implication here that petrified people aren't truly dead even if their bodies are damaged or is Arthur actually capable of resurrecting the dead? The latter option seems questionable to me, since in the Cursed by Light movie we see him construct a massive graveyard in the ruins of Camelot. If his Chaos powers include the ability to bring the dead back to life, why not just revive everyone instead? Sure, the power to outright resurrect people is a godly ability that is fitting for someone in control of Chaos, but it also opens a pretty major can of worms. He could be bringing back the likes of Monspeet, Derieri, Drole, Gloxinia, the demon Gowther, Escanor, the Original Demon and maybe even the deities. There would have to be some kind of limitations to it or things would get completely out of hand, not to mention repetitive. Imagine the DK coming back for yet another round of fighting. Hopefully Arthur just glued Galand back together like some sort of a 3D jigsaw puzzle.
Lastly, I could be wrong, but didn't Nakaba mention in some kind of a databook that the armor is Galand's body and that there is nothing underneath it? That seems to go against the Galand that we see here. When I first saw the pics I considered the possibility that Arthur had just grafted some demon limbs onto his knights, but the translations seem to suggest that these two are in fact the real thing. I guess that means Nakaba either change that detail(assuming I'm not remembering it wrong) or Arthur gave Galand a brand new fleshy body.