Action Type for Dance of Dawn Deed

[Gallant Armor]

Dance of Dawn:

At 11th level, whenever a whirling dervish is in conditions of dim light or brighter and hits with a melee attack, she can spend 1 panache point to reflect the light off her blade into the eyes of her target. That opponent is blinded for 1 round. A successful Fortitude save (DC = 10 + 1/2 the whirling dervish’s class level + her Dexterity modifier) negates this effect. This deed replaces bleeding wound.

Basically as the title says, I'm trying to figure out the action type for the Dance of Dawn deed from the Whirling Dervish Swashbuckler archetype.

I know the default is standard action, but since this triggers on a successful melee attack it would have to be immediate, swift, or free logically. I didn't see anything in the Swashbuckler write-up about deeds defaulting to a particular action type so any thoughts or opinions would be appreciated.

[SlimGauge]

I'd say it's part of whatever action you used to make the triggering melee attack.