As far as Silence goes, Eiko can probably equip Loudmouth skill.
Fixed.
Is she equipping some armor to get this skill, or are you seeing this as learnable to Eiko so that she doesn't HAVE to equip the required armor to learn it?
And has to equip the armor to get everything, for both Loudmouth and Fire halving... She's either losing 32 Defense and 19 MDEF for going for the Golden Hairpin/Adaman Vest, (and losing Earth/Wind immunity in the process), Mage's Hat/Adaman Vest for -32 Defense and -37 MDEF ( same downside), Silk Robe/Black Hood for -30 Defense and -24 MDEF (Which she does NOT want, since the Silk Robe makes her Fire WEAK instead), OR... For a meager -4 Defense and -24 MDEF, she can go for White Robe/Black Hood, which STILL makes her Fire Weak.
Yeah, she's either vulnerable to Silence, weak to fire, or has a defense rating of one-third average. Not good...
Carbuncle's Boost scene makes it Reflect+Protect normally. If you don't let Eiko have Boost, then I guess she's only casting MT Reflect, MT Shell or MT Haste.
Moonstone: "Jewel Light" casts Shell (short animation) or Shell and Protect (long animation)
If you let her have Boost, she can arguably cast Shell and Protect on the entire party?
This FAQ confirms Bard's statement:
NOTE: To make Fenrir change to 'Millennial Decay,' learn the summon and
equip a Maiden's Prayer item. Fenrir'll do wind-elem damage, now.
Anytime Carbuncle is shown at full animation, it gains the ability
to add Protect to whatever status it's normally supposed to.
Still, I hope you're still fully aware that a full-party Shell is also halving your magical healing again... Also, it still leaves other characters vulnerable to being Silenced anyway (and a full party Cura, in this case, is... Since you only have 4 PCs... What,
25% 50% average FFIX HP in healing anyway, so only sort of useful?).
Granted this is me nitpicking, so... Feel free to ignore me.