You receive this quest from Welda in Village of Albion
She asks you to persuade the god Nodens and the goddess Coventina to give you their tears to water the Tree of Promise.
Go to the temple of the goddess Coventina in the Cliffs of Balor and the sanctuary of the god Nodens in River Lub and persuade them to give you their tears so you may revive the Tree of Promise.
You will receive the Rejuvenate the Tree Quest.
You will need to get to Nodens and clear his mind with the Chalice of Restoration.
Refer to the Persuade the Giant quest for help with this.
When you free Nodens, go to the Temple of Nodens in River Lub and touch the Northern statue to get the Nodens' Tears Potion.
To get Convetinas tears, go to the Cliffs of Balor.
Enter the Temple of Conventina.
Touch the Northern statue.
You will receive the Coventina's Tears Potion.
Return to the Village of Albion.
Touch the Tree in the western part of the Village.
You will use the tears of Nodens and Conventina to water the sick tree.
Return to Welda.
The Rejuvenate the Tree quest will be solved.
You will receive the King's Guard's Ring Mail, King's Guard's Helm, and 2 Mutten Stew Potions.