pf2e.fyi
From Pathfinder #159: All or Nothing, which isn't enabled.

Subtle Shank

FEAT 8
UNCOMMONFLOURISHROGUE
Activity 2 actions
Access Help either the Washboard Dogs or the Diobel Sweepers destroy their rival.
Requirements You have a melee weapon of light bulk Concealed on your person via the Stealth skill, and the target isn't aware of it.

You draw a concealed weapon, attack with it, and then hide it away again in one smooth motion. Interact to draw the weapon, Strike with that weapon, and then Conceal it with a Stealth check. The target is Off-Guard for this attack.

Pathfinder #159: All or NothingOGL