What's the Statue of Yenwood in the Endless Paths for? I assumed I could give him his sword (so I went all the way back to the Gilded Vale to buy it back from where I sold it) but it doesn't seem to work.

That's exactly what you do. You give the Endless Paths Level 3 Statue of Yenwood it's sword, Resolution, a Sabre dropped by a Greater Black Ooze in Endless Paths level 4.

 

If that's not working, you've run into a bug.

You mustn't have it equipped when interacting with the statue. Perhaps that's a bug?

Right, I thought it would be his signature sword - Whispers of Yenwood - silly me.

 

Thanks anyway.

Whispers of Yenwood was the (slightly cursed) sword from the Keep's warden. Resolution was the Earl's family sword.