Being a basic ally with piercing gives Swordsman a useful niche in the crowded ally slot. Leadership has a cheaper option with Black Knight, and Aggression has Wolverine, who outputs more damage overall, but Justice and Protection might be interested. Swordsman's response does two interesting things. 1 - if he is given a tough status (Ready for Action, Muster Courage), he can block an attack and activate in the same round. 2 - since the response is after a boost is turned face up, you can wait to block with him until he's guaranteed to soak a large attack. Especially with the Avenger trait, Swordsman has enough things adding up to make him reasonably playable.