Make a small change that would break a class completely.

[Kuwagami]

Summoner = Bane is no longer limited to 3 targets

you mean, like it was before the 2.1 (or was it 2.2 ?) nerf ?

here my list :

BLM : no monster is immune anymore to sleep
BRD : swiftsong in battle (I would have said give us the original RoD back, but now WARs have it, so.. yeah...)
WAR : overpower is now MP-based (of course, their MP pool remains super low)
PLD : stances are no longer on GCD and do not break combo anymore (second one should be QoL thing. meh)
SCH : a critical embrace shields the target
MNK : GL has a 20 seconds duration
DRG : ellusive jumps actually counts you out of the AoEs when you're out and not when you land (oh maybe that should be an other QoL thingie instead ? ;D )
WHM : shroud of saints nullifies hate generation for its duration on top of the current effects

The only "nerf" about Bane was the skill description, not the skill itself. Only the description got changed.

is that so ? my ACN was lv15~ish at that time so I always thought it was a nerf. thanks for the enlightenment

[Felis]

you mean, like it was before the 2.1 (or was it 2.2 ?) nerf ?

The only "nerf" about Bane was the skill description, not the skill itself. Only the description got changed.

[NinjaTaru72]

Sch - Heals cast by eos now add galvanize, this does not erase the adloquium galvanize, and doesn't have a timer.

[Bishop81]

Ruin II now does 9999 damage.

:P

[DarkmoonVael]

SCH, once you reach 500 crit, all spells you cast now automatically crit. Fairy embrace skill is now replaced by fairy Adloquium.

[Vurtney]

PLD - Flash now has an added effect of DEATH level 1, 2, 3, 4 and 5. If the target is immune to DEATH, Flash will debuff the target with DOOM on a 1 second timer. Flash will now work on NPC's, player characters and players using virtual headsets (you have been warned)

[Imakun]

WHM
Medica is now Curaga. Medica II is now Curaja. Yes I hate the name Medica.
Also Esunaga is reality and Benediction hits the whole party but has a longer recast time.

SMN
Contagion is now a SMN ability that consumes a stack of Aetherflow when used. Bane, on the other hand, doesn't anymore and costs 150 MP.
Garuda's Contagion is replaced by 'Ill Wind' which inflicts Miasma and Bio on a target.

SCH
Fairies will now sit on your shoulder and/or head while idle. Yaaaay!

[Magis]

As BLM, all spells used together always burn enough mp to put you just under the amount needed to use Blizzard III.

[BlackenedTiamat]

a Passive Ability for DRGs - "upon your death, cause an 5 yalm aoe that inflicts damage with a potency of 500."

[Natsuno]

Book smack causes the target to fall down unconscious for the remainder of the fight