Of all classes, I would hope that Swashbuckler would be the one that can disarm a weapon, catch it out of the air with his off hand, and hold both swords crossed at his opponent's throat as a single action. If you must break it up into three actions, I would say "Disarm. Catch. Finisher." Maybe she would have an ability that gives her a critical success when she gets a success on a disarm check?
Overall Disarm was pretty underpowered in 2e, which I kind of liked. It fits with the action system. It is something that everyone can do if they are trained in the skill, but no one does it so well that they completely cripple a melee fighter in one action. These techniques could easily fit in the Fencer's style. It doesn't need its own option.