What does the "Blessing of the Mermaids" do?

After completing puzzle 5 of Turquoise Cove, a mermaid gave me the "Blessing of the Mermaids". Up until now, completing NPC challenges has unlocked free single-use items that can be picked at a shop. However, completing the mermaid's challenge didn't add any items to the shop or my inventory.

What does the "Blessing of the Mermaids" do?

Solution 1:

I've reached 100% completion in PictoQuest and was unable to find any use for the "Blessing of the Mermaids".

Completing Turquoise Cove 11 for the Fisherman in Love earns you the "Curse of the Mermaids", which I was also unable to find a use for. This makes me believe both of these "items" are jokes rather than actual rewards.