EastScape Wikibuilt from the game itself

Stardust Polish

“Rub it on your blade: for 300 landed melee hits, 20% of each hit is Sun (you heal 15% of that Sun part, and monsters weak to Sun take more). One oil at a time. From the Star Tent. Bound: it can't be traded, sold or dropped.”

Sold by

The Star Tent, in Cloudreach: 250 Star Fragments. World events.

Can't be traded. Your stardust polish can't change hands.