[Fern]

Fighting Mirrored can be pretty awful. I don't think there's much to add that hasn't already been said in the OP (or the other threads), it's the standard go-to for meta tanks with shields since they want to start guarding with about 1M most of the time. Guard Break is a status that only barely exists and lasts for a very short time that doesn't compensate for the drawbacks from the skills you'd normally see it happen with (Lance de Lion, Reaper Scythe, Light Tomahawk.)

If number changes are hypothetically not an option then there's the idea of making it so you need to have Guard LV30 or higher for Mirrored to do the retaliation damage, but I'm honestly not entirely sure if that's slapping it too hard.