After getting the flower, climb up using the wooden plank on the right.
There's a save point after coming up. You can talk to the person on the left, and there's a treasure chest on the right.
Obtain the support accessory "Frostspire" from the treasure chest. (Spent quite a while today figuring out this area with no visibility, which delayed things a bit. I'll aim to finish it in the next couple of days.)
