I don't have a log, and I haven't tried to reproduce this, so this may be a premature report, but... In a recent game against Gwald, I cast Firestorm or something, his dwarf warrior's Barbed Platemail popped up, and the die roll for it incremented upward from a failed roll to a successful one, as though affected by a Harness. I saw no Harness in his hand, and was confused. He had one unrevealed card, older than the Barbed Platemail. The next turn, I again damaged him, and this time the Barbed Platemail didn't reduce the damage to zero so his Enchanted Harness–indeed, the oldest card in his hand—popped up to reduce damage, this time revealing itself. Has anyone else ever experienced something like this, where an armor gets the harness boost without revealing the harness?
Yeah, I've seen something similar happen before. I don't remember the details, just thinking "huh, that's weird..."
It's just that any cards that modify dice rolls animate and take effect as normal, whether they are known or not. If you are using Massive Chop, you will also see block rolls be reduced even if the card isn't revealed.
Massive Chop should also show itself imo, although I remember from AA it doesn't, yes. Was although always possible to deduce opp had it when his blocks' rolls went lower so would be better to reveal such cards.
Bad luck is an attachment so ya always revealed. As for the harness, my guess would be that they reveal themselves only if they have to trigger an armor roll. In your case it didn't revealed itself the first time as the barbed mail reduced all damages (the 4 of FS) to 0, making any further armor roll pointless and thus skipped. If the two armors switched position in your opponant's hand, then you would have seen both armors as the harness can't reduce the damages of the FS to 0.