Looked at this, but it didn't register the items you were trying to sell. I have nfc why it keeps bugging out for you.
A broker's aide shows a shining steel breastplate to an armwear broker.
* R:23094 S:Inside HP:Healthy SP:Bursting MV:Fresh >
A broker's aide says 'Unfortunately, these seem to be in less than perfect condition.'
A broker's aide drops a shining steel breastplate.
And that 15+ times, every single time.
Considering I can't magically make item condition worse, I didn't test the helmet, but it's all the same mobol, so if it works with a plate, it should work with a helmet.