While the battle is claimed to be optional, you can't get the Azure Jewel ( assuming an essential grab ) until you defeat it, I can't. Following a guide, I start off with Quickening -- everyone has at least two, except for Vossler who's a guest still -- at best I can take a huge quarter of its health. Then it recommends Aero spells, which it's weak to, the one person who can hardly does any damage. I've equipped Shell beforehand was it was told it'd reduce the chances of negative effects, I call bull as both Vaan ( often the first ) and Fran have been sent to the void / X-Zone, unsure if it was referring to blind or the weird instant, yet annoying, kill spell -- at that point it's down half its health with little time before it runs out.
My current team is:
Vaan - 26.
Fran - 20 ( initially Basch but switched to Fran as she had the spells I need that it was weak to. )
Ashe - 25.
Vossler - 28.
EDIT: I managed to beat it with little causalities, yet a really close call by the time one of my members land the finishing blow, thank you all!
Touching the Azure Jewel is optional and not essential at all.
The reward from beating the first Demon Wall is one Scathe Mote.
X-Zone absolutely hits all the time. Shell would be for preventing the other status effects that they’re capable of throwing at you. I know you’ve already won at this point, but Aero is augmented by equipping a Cherry Staff on your caster, and then Reflect on your own party, if you have access to that, you’ll get 4x hits per cast. In addition, Vossler has all four breaks, so he can spam Shear to make the spells hit harder as well.
I ran from first D wall
Dude, this thing kicked my ass and I was OP.