Petruccio's feather is an item found in Senntisten. Finding it and returning it completes the eponymous achievement: Petruccio's Feather.
Attempting to take the feather prompts the message "As you reach toward it, the feather floats into your hand", while inspecting it prompts the message "A small silver feather. You sense this belongs to someone". Returning it to the chest yields the message "As you open the chest, the feather floats from your pocket into the box, joining a set of other feathers."
The feather can be found in the barricade below where Commander Zilyana is positioned.
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- The item is a reference to Petruccio Auditore da Firenze from Assassin's Creed 2, who started a sidequest to retrieve feathers.