5th dnd – What is the effect of "the weapon of the attack" that inflicts additional damage?

The Cavalier Fighter & # 39; s Unshakable brand said

If a creature marked by you deals damage
to anyone other than you, you can do a special scrum
weapon attack against the creature marked as a bonus
action on your next turn. You have an advantage over the
jet of attack, and if it strikes, the weapon of the attack deals in addition
to the target equal to half of your combatant level.

What is the meaning of the The weapon of the attack deals additional damage? Is it the same as you inflict additional damage clauses (so just add damage to the damage roll of this attack)? Or does it mean that it is a separate case of damage (save twice the concentration saved)? Or maybe just a typo, and he should read the attack of the weapon inflicts additional damage? Or does the weapon suddenly start doing more damage to this target?

It sounds very strange to me and I do not remember seeing anything like it.