Maybe it's a special thing for Goko? Like, the actual card is just Knight, but on Goko it will appear as (Sir/Dame) (Your Name).
That's a good idea. Maybe, it is Goko exclusive online only promo.
Here's the description from an online randomizer:
"Shuffle together all ten Knight cards to form a single Supply pile, with only the top card visible."
That randomizer also seems to reveal the names of all the remaining Dark Ages cards. I believe this is all of them:
Catacombs (5 cost)
Counterfeit (0 cost treasure)
Death Cart (4 cost)
Forager (5 cost)
Hunting Grounds (6 cost)
Junk Dealer (5 cost)
Marauder (4 cost)
Market Square (3 cost reaction)
Mystic (5 cost)
Rebuild (5 cost)
Rebuild (5 cost)
Rogue (5 cost)
Storeroom (3 cost)
Urchin (3 cost)
Wandering Minstrel (4 cost)
Whenever there are
Market Squares Urchins, there is a (non-Supply) pile of 10 Mercenaries.