I understood this to mean that a ship is 'damaged' if the ship is below its starting health. Ie if it has shields, its list at least one or if not originally shielded, it has a damage card.
This applies to Wullffwaro in the Rebels and Null in First Order.
Also, is there a distinct difference between 'damaged' and 'suffer damage' as noted on Stealth Device?
I realise it might come down to RaW. I'm more interested to make sure I'm playing Wullffy right - I didn't ever get him during 1e.