I'll spare the diatribe on anti-fun mechanics and how Falkow at its purest embodies them. But in any case, I think EX mermaid is fine. Simply, she's good at her job, which is to be a unit that your opponent has to bend over backwards to take down, but doesn't really do much harm herself. And honestly, it's always the Refess players whining the loudest when *any* other sphere gets a unit that's exceptional for the sphere, but not for Refess.
Falkow: Elite Fencer, old Emana (60 HP version), now EX merm.
Gowen: Rhino, old Dilate.
Lawtia: Refess sort of has had Lawtia's number forever, hence not much moaning over EXCak (which nevertheless still got nerfed) and Broken Virus.
And honestly, I say that the whiners can go eat a blueberry muffin. I'm sorry, but Refess does not and should not have a monopoly on units that make your opponent press "rest" instead of "attack". We're 11 sets into the game and only going to get more cards. At some point, we're going to have exceptions to the rule. Refess was supposed to be the faction of "slow, weak attack, but tough" units. Yet now, the best Refess metas are the ones that break that rule. Buncles at their slowest are agi 3, for their generals. At their fastest? 6 (diamond buncle buffing off of jade, agate, or amethyst). Shrine Knights? Judie/Verlaat?
IMO this whining is much ado over nothing--just the usual Refess players being butthurt that some other faction actually has a tank that doesn't just get rolled over--and worst of all, it's *Falkow*, who has the very bane of Refess's existence--returns and DIONDORA (oh noes!).
And considering how many other tanks the balancing team has nerfed, I say for once, make the right move, don't be dumb, don't listen to the whiners, and let the exceptions persist. Refess shouldn't have a monopoly on tanks.