In Xanathar's Guide to Everything (p. 30), the Cavalier Fighter's Unwavering Mark feature says:
In addition, if a creature marked by you deals damage to anyone other than you, you can make a special melee weapon attack against the marked creature as a bonus action on your next turn. You have advantage on the attack roll, and if it hits, the attack's weapon deals extra damage to the target equal to half your fighter level.
What is the meaning of "the attack's weapon deals extra damage"?
Does it mean the same as "you deal extra damage" clauses (so just add damage to that attack's damage roll)? Or does it mean it is a separate instance of damage (roll twice for concentration saves)? Or is it maybe just a typo, and it should read "the weapon attack deals extra damage"? Or does the weapon suddenly start doing more damage to that target?
It seems like very strange wording to me, and I don't recall seeing anything similar.