About the holy light mission,

1 Go to the Elder Mansion and talk to Ruby, and then go to the Fairy Tale Village Library and talk to the librarian. Weitz will give you a book.

Call Hans, the delivery instructor, and talk to the evil moss in the Presbyterian House.

As far as I know, I was talking to Hans, looking for evil moss.

4 The monster in the Cave of Life will let you find the root of life, the dark dragon king (you must complete the transformation task) before it falls off in the team task.

Summon the root of life to the evil moss to gain skills and light.