I'm just gonna put it out there:
With the number of times that the Mystic Knights get specifically told, "Hey, don't ever give up your weapons, ever, for any reason, ever," then still proceed to do that like five episodes later...
... we really should've had an episode where Fin Varra's like, "Oh no. The Amethyst Fairy Moon has risen. Quick, everyone! Lock your weapons in this special crate! It's the only place where they can avoid the evil moon beams that'll trigger a MOST DANGEROUS curse!"
And the rest of them look at each other, look at Fin Varra, look at each other again, and then say, "... Yeah, no, we're not gonna fall that."
Because this show was pretty damn good at continuity! They actually learned from their mistakes and experiences - except for this specific one about not giving up their weapons 😵💫 - and that was almost a subversion of other kid shows at the time. So to subvert it again but have Rohan be like, "Nuh-uh. The real Fin Varra wouldn't tell us to lock up our weapons ever," and have Angus say, "And if he did, he'd come up with something way better than 'Cursed Fairy Moon' 🙄" would've been hilarious.
I could honestly picture them trapping Fin Varra or something, thinking he was an imposter. Worse if Aideen tried to convince them and they didn't believe her, like it was some strange spell on all the fairies and it was spreading. Even worse if Cathbad hasn't heard about it, or seems to 'suddenly believe Fin Varra' like Cathbad's fallen under the spell too.
And then obviously, the curse happens and the weapons transform and they uhhhhhh have to fight their living armour or something? Idk.
It'd also make sense for merchandising. You could have Fin Varra agree that these weapons are too volatile for humans to handle after all, since they can't tell the difference between a trick and a real warning. So instead, they're off to have new weapons forged. Bam - new toys to sell.
And it was the 90s so I'm assuming they wouldn't realize they're telling kids to question authority until after it aired lmao, like how Disney didn't catch that their new Pinocchio live-action movie had a scene essentially telling kids that lying actually solved a lot of problems, do it all the time, lie.
But I guess you could have the episode be about how easily the Mystic Knights get tricked, and how if they'd paid closer attention to the warning signs, they wouldn't've been tricked. Which - being the 90s - would be period-appropriate victim-blaming, so we're okay there 👍🏽
Anyway, just a fun idea I had. :)